Families Electronegativity Atomic radius 1st ionization Physical state
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Core properties
Atomic mass 1.008 u
Electron configuration 1s1
Standard state gas
Common oxidation states +1, −1
Electronegativity 2.2 Pauling
Electron affinity 0.754 eV
First ionization energy 13.598 eV
Covalent 31 pm
van der Waals 120 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
water, hydrocarbons, organic matter and natural gas
Typical reactivity
combustible; H₂ reacts exothermically with O₂ and forms hydrides with many elements.
Discovery and short history
Year / era: 1766
Hydrogen was recognized as a distinct substance in the 18th century; its name refers to the formation of water.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 4.003 u
Electron configuration 1s2
Standard state gas
Common oxidation states 0
Electronegativity —
Electron affinity —
First ionization energy 24.587 eV
Covalent 28 pm
van der Waals 140 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
natural gas; also generated by radioactive decay of U and Th
Typical reactivity
very low reactivity; heavier members, especially Xe and to a lesser extent Kr, form compounds under suitable conditions.
Discovery and short history
Year / era: 1868
Helium was first observed in the solar spectrum and identified on Earth later—a rare case of astronomical discovery preceding laboratory isolation.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 6.941 u
Electron configuration [He] 2s1
Standard state solid
Common oxidation states +1
Electronegativity 0.98 Pauling
Electron affinity 0.618 eV
First ionization energy 5.392 eV
Covalent 128 pm
van der Waals 220 pm
Ionic radii
Ion
CN
Radius / pm
Note
Li+1
6
76
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
crimson red
~670.8 nm
Observed color depends on the volatile species and flame conditions; it is not the color of bulk elemental material.
Occurrence and minerals
spodumene, lepidolite, petalite and brines
Typical reactivity
highly electropositive metal: rapidly oxidizes and reacts with water to form hydroxide and H₂; reactivity increases down the group.
Discovery and short history
Year / era: 1817
Identified in 1817, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 9.012 u
Electron configuration [He] 2s2
Standard state solid
Common oxidation states +2
Electronegativity 1.57 Pauling
Electron affinity —
First ionization energy 9.323 eV
Covalent 96 pm
van der Waals 190 pm
Ionic radii
Ion
CN
Radius / pm
Note
Be+2
6
45
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
beryl, bertrandite and phenakite
Typical reactivity
electropositive metal; mainly forms M²⁺ and basic oxides/hydroxides. Water reactivity generally increases down the group.
Discovery and short history
Year / era: 1798
Identified in 1798, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 10.812 u
Electron configuration [He] 2s2 2p1
Standard state solid
Common oxidation states +3
Electronegativity 2.04 Pauling
Electron affinity 0.277 eV
First ionization energy 8.298 eV
Covalent 84 pm
van der Waals 180 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
green for volatile boron compounds
green molecular emission; not a simple atomic-line test
Observed color depends on the volatile species and flame conditions; it is not the color of bulk elemental material.
Occurrence and minerals
borax, kernite and colemanite
Typical reactivity
intermediate metal/nonmetal behavior; covalent bonding and structure-dependent properties are common.
Discovery and short history
Year / era: 1808
Identified in 1808, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 12.011 u
Electron configuration [He] 2s2 2p2
Standard state solid
Common oxidation states +4, +2, −4
Electronegativity 2.55 Pauling
Electron affinity 1.263 eV
First ionization energy 11.26 eV
Covalent 76 pm
van der Waals 170 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
graphite, diamond, carbonates, coal and organic matter
Typical reactivity
reactivity strongly depends on allotrope; supports an enormous covalent chemistry and oxidizes to CO/CO₂.
Discovery and short history
Year / era: Ancient
Known since antiquity as charcoal and graphite; diamond was recognized as an allotrope of carbon much later.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 14.007 u
Electron configuration [He] 2s2 2p3
Standard state gas
Common oxidation states +5, +3, +2, +1, −3
Electronegativity 3.04 Pauling
Electron affinity —
First ionization energy 14.534 eV
Covalent 71 pm
van der Waals 160 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
atmosphere; natural nitrates and organic matter
Typical reactivity
N₂ is rather unreactive at room temperature because of the triple bond; forms nitrides, ammonia and many oxides.
Discovery and short history
Year / era: 1772
Nitrogen was identified in the 18th century while studying the fraction of air that does not support combustion or respiration.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 15.999 u
Electron configuration [He] 2s2 2p4
Standard state gas
Common oxidation states −2, −1, +2
Electronegativity 3.44 Pauling
Electron affinity 1.461 eV
First ionization energy 13.618 eV
Covalent 66 pm
van der Waals 155 pm
Ionic radii
Ion
CN
Radius / pm
Note
O−2
6
140
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
oxides, silicates, carbonates, water and atmosphere
Typical reactivity
strong oxidizer; supports combustion and forms oxides with almost all elements.
Discovery and short history
Year / era: 1774
Oxygen was isolated in the 18th century and became central to Lavoisier’s new interpretation of combustion.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 18.998 u
Electron configuration [He] 2s2 2p5
Standard state gas
Common oxidation states −1
Electronegativity 3.98 Pauling
Electron affinity 3.339 eV
First ionization energy 17.423 eV
Covalent 57 pm
van der Waals 150 pm
Ionic radii
Ion
CN
Radius / pm
Note
F−1
6
133
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
fluorite, fluorapatite and cryolite
Typical reactivity
extremely strong oxidizer; reacts with nearly all elements and many materials.
Discovery and short history
Year / era: 1886
Identified in 1886, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 20.18 u
Electron configuration [He] 2s2 2p6
Standard state gas
Common oxidation states 0
Electronegativity —
Electron affinity —
First ionization energy 21.565 eV
Covalent 58 pm
van der Waals 154 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
trace constituent of the atmosphere
Typical reactivity
very low reactivity; heavier members, especially Xe and to a lesser extent Kr, form compounds under suitable conditions.
Discovery and short history
Year / era: 1898
Neon was identified near the end of the 19th century during separation of noble gases from liquefied air.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 22.99 u
Electron configuration [Ne] 3s1
Standard state solid
Common oxidation states +1
Electronegativity 0.93 Pauling
Electron affinity 0.548 eV
First ionization energy 5.139 eV
Covalent 166 pm
van der Waals 240 pm
Ionic radii
Ion
CN
Radius / pm
Note
Na+1
6
102
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
intense yellow
589.0 / 589.6 nm
Observed color depends on the volatile species and flame conditions; it is not the color of bulk elemental material.
Occurrence and minerals
halite, albite, trona and brines
Typical reactivity
highly electropositive metal: rapidly oxidizes and reacts with water to form hydroxide and H₂; reactivity increases down the group.
Discovery and short history
Year / era: 1807
Metallic sodium was isolated by Humphry Davy by electrolysis of caustic soda.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 24.305 u
Electron configuration [Ne] 3s2
Standard state solid
Common oxidation states +2
Electronegativity 1.31 Pauling
Electron affinity —
First ionization energy 7.646 eV
Covalent 141 pm
van der Waals 220 pm
Ionic radii
Ion
CN
Radius / pm
Note
Mg+2
6
72
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
magnesite, dolomite, carnallite and seawater
Typical reactivity
electropositive metal; mainly forms M²⁺ and basic oxides/hydroxides. Water reactivity generally increases down the group.
Discovery and short history
Year / era: 1755
Identified in 1755, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 26.982 u
Electron configuration [Ne] 3s2 3p1
Standard state solid
Common oxidation states +3
Electronegativity 1.61 Pauling
Electron affinity 0.441 eV
First ionization energy 5.986 eV
Covalent 121 pm
van der Waals 210 pm
Ionic radii
Ion
CN
Radius / pm
Note
Al+3
6
53.5
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
bauxite, feldspars, micas and clays
Typical reactivity
p-block metal with moderate reactivity, multiple oxidation states and a growing inert-pair effect for heavier members.
Discovery and short history
Year / era: 1825
Identified in 1825, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 28.086 u
Electron configuration [Ne] 3s2 3p2
Standard state solid
Common oxidation states +4, +2, −4
Electronegativity 1.9 Pauling
Electron affinity 1.385 eV
First ionization energy 8.152 eV
Covalent 111 pm
van der Waals 210 pm
Ionic radii
Ion
CN
Radius / pm
Note
Si+4
6
40
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
quartz and most common silicate minerals
Typical reactivity
intermediate metal/nonmetal behavior; covalent bonding and structure-dependent properties are common.
Discovery and short history
Year / era: 1824
Identified in 1824, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 30.974 u
Electron configuration [Ne] 3s2 3p3
Standard state solid
Common oxidation states +5, +3, −3
Electronegativity 2.19 Pauling
Electron affinity 0.746 eV
First ionization energy 10.487 eV
Covalent 107 pm
van der Waals 195 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
apatite and phosphate rock
Typical reactivity
forms covalent compounds and increasingly metallic species down the group; −3, +3 and +5 are important oxidation patterns.
Discovery and short history
Year / era: 1669
Phosphorus was isolated in the 17th century and is commonly regarded as the first element discovered in the modern era.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 32.067 u
Electron configuration [Ne] 3s2 3p4
Standard state solid
Common oxidation states +6, +4, −2
Electronegativity 2.58 Pauling
Electron affinity 2.077 eV
First ionization energy 10.36 eV
Covalent 105 pm
van der Waals 180 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
native sulfur, pyrite, gypsum and metal sulfides
Typical reactivity
forms chalcogenides and oxides; chemistry shifts from strongly oxidizing oxygen toward more metallic behavior down the group.
Discovery and short history
Year / era: Ancient
Known and used before modern chemistry; recognition as an element belongs to the later development of the discipline.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 35.453 u
Electron configuration [Ne] 3s2 3p5
Standard state gas
Common oxidation states +7, +5, +3, +1, −1
Electronegativity 3.16 Pauling
Electron affinity 3.617 eV
First ionization energy 12.968 eV
Covalent 102 pm
van der Waals 180 pm
Ionic radii
Ion
CN
Radius / pm
Note
Cl−1
6
181
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
halite, sylvite, brines and seawater
Typical reactivity
strong tendency to form X⁻; typical oxidizing/halogenating chemistry, with reactivity generally decreasing down the group.
Discovery and short history
Year / era: 1774
Chlorine was prepared in the 18th century; it was only later recognized as an element rather than an oxygen-containing compound.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 39.948 u
Electron configuration [Ne] 3s2 3p6
Standard state gas
Common oxidation states 0
Electronegativity —
Electron affinity —
First ionization energy 15.76 eV
Covalent 106 pm
van der Waals 188 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
atmosphere; separated industrially from air
Typical reactivity
very low reactivity; heavier members, especially Xe and to a lesser extent Kr, form compounds under suitable conditions.
Discovery and short history
Year / era: 1894
Identified in 1894, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 39.098 u
Electron configuration [Ar] 4s1
Standard state solid
Common oxidation states +1
Electronegativity 0.82 Pauling
Electron affinity 0.501 eV
First ionization energy 4.341 eV
Covalent 203 pm
van der Waals 280 pm
Ionic radii
Ion
CN
Radius / pm
Note
K+1
6
138
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
lilac-violet
~404 nm; 766.5 / 769.9 nm lines
Observed color depends on the volatile species and flame conditions; it is not the color of bulk elemental material.
Occurrence and minerals
sylvite, carnallite, feldspars and micas
Typical reactivity
highly electropositive metal: rapidly oxidizes and reacts with water to form hydroxide and H₂; reactivity increases down the group.
Discovery and short history
Year / era: 1807
Potassium was the first metal isolated by Davy using electrolysis, shortly before sodium.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 40.078 u
Electron configuration [Ar] 4s2
Standard state solid
Common oxidation states +2
Electronegativity 1 Pauling
Electron affinity —
First ionization energy 6.113 eV
Covalent 176 pm
van der Waals 240 pm
Ionic radii
Ion
CN
Radius / pm
Note
Ca+2
6
100
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
orange-red / brick red
~616–622 nm prominent region
Observed color depends on the volatile species and flame conditions; it is not the color of bulk elemental material.
Occurrence and minerals
calcite, dolomite, gypsum, fluorite and apatite
Typical reactivity
electropositive metal; mainly forms M²⁺ and basic oxides/hydroxides. Water reactivity generally increases down the group.
Discovery and short history
Year / era: 1808
Identified in 1808, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 44.956 u
Electron configuration [Ar] 3d1 4s2
Standard state solid
Common oxidation states +3
Electronegativity 1.36 Pauling
Electron affinity 0.188 eV
First ionization energy 6.561 eV
Covalent 170 pm
van der Waals 230 pm
Ionic radii
Ion
CN
Radius / pm
Note
Sc+3
6
74.5
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1879
Identified in 1879, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 47.867 u
Electron configuration [Ar] 3d2 4s2
Standard state solid
Common oxidation states +4, +3, +2
Electronegativity 1.54 Pauling
Electron affinity 0.079 eV
First ionization energy 6.828 eV
Covalent 160 pm
van der Waals 215 pm
Ionic radii
Ion
CN
Radius / pm
Note
Ti+4
6
60.5
Shannon
Ti+3
6
67
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
ilmenite and rutile
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1791
Identified in 1791, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 50.944 u
Electron configuration [Ar] 3d3 4s2
Standard state solid
Common oxidation states +5, +4, +3, +2
Electronegativity 1.63 Pauling
Electron affinity 0.525 eV
First ionization energy 6.746 eV
Covalent 152 pm
van der Waals 205 pm
Ionic radii
Ion
CN
Radius / pm
Note
V+5
6
54
Shannon
V+4
6
58
Shannon
V+3
6
64
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
vanadinite, patronite and carnotite
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1801
Identified in 1801, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 51.996 u
Electron configuration [Ar] 3d5 4s1
Standard state solid
Common oxidation states +6, +3, +2
Electronegativity 1.66 Pauling
Electron affinity 0.666 eV
First ionization energy 6.767 eV
Covalent 139 pm
van der Waals 205 pm
Ionic radii
Ion
CN
Radius / pm
Note
Cr+3
6
61.5
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
chromite
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1797
Identified in 1797, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 54.938 u
Electron configuration [Ar] 3d5 4s2
Standard state solid
Common oxidation states +7, +4, +3, +2
Electronegativity 1.55 Pauling
Electron affinity —
First ionization energy 7.434 eV
Covalent 139 pm
van der Waals 205 pm
Ionic radii
Ion
CN
Radius / pm
Note
Mn+2
6
83
Shannon, high spin
Mn+4
6
53
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
pyrolusite, rhodochrosite and manganite
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1774
Identified in 1774, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 55.845 u
Electron configuration [Ar] 3d6 4s2
Standard state solid
Common oxidation states +3, +2
Electronegativity 1.83 Pauling
Electron affinity 0.163 eV
First ionization energy 7.902 eV
Covalent 132 pm
van der Waals 205 pm
Ionic radii
Ion
CN
Radius / pm
Note
Fe+2
6
78
Shannon, high spin
Fe+3
6
64.5
Shannon, high spin
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
hematite, magnetite, siderite and goethite
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: Ancient
Known since antiquity; iron metallurgy marked one of the major technological transitions in human history.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 58.933 u
Electron configuration [Ar] 3d7 4s2
Standard state solid
Common oxidation states +3, +2
Electronegativity 1.88 Pauling
Electron affinity 0.661 eV
First ionization energy 7.881 eV
Covalent 126 pm
van der Waals 200 pm
Ionic radii
Ion
CN
Radius / pm
Note
Co+2
6
74.5
Shannon, high spin
Co+3
6
54.5
Shannon, low spin
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
cobaltite, skutterudite and Ni–Cu ores
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1735
Identified in 1735, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 58.693 u
Electron configuration [Ar] 3d8 4s2
Standard state solid
Common oxidation states +3, +2
Electronegativity 1.91 Pauling
Electron affinity 1.156 eV
First ionization energy 7.64 eV
Covalent 124 pm
van der Waals 200 pm
Ionic radii
Ion
CN
Radius / pm
Note
Ni+2
6
69
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
pentlandite and lateritic nickel ores
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1751
Identified in 1751, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 63.546 u
Electron configuration [Ar] 3d10 4s1
Standard state solid
Common oxidation states +2, +1
Electronegativity 1.9 Pauling
Electron affinity 1.228 eV
First ionization energy 7.726 eV
Covalent 132 pm
van der Waals 200 pm
Ionic radii
Ion
CN
Radius / pm
Note
Cu+2
6
73
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
blue-green (compound-dependent)
~510–522 nm commonly observed
Observed color depends on the volatile species and flame conditions; it is not the color of bulk elemental material.
Occurrence and minerals
chalcopyrite, bornite, chalcocite, malachite and native copper
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: Ancient
Known since antiquity and used early as native metal and later in bronze alloys.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 65.39 u
Electron configuration [Ar] 3d10 4s2
Standard state solid
Common oxidation states +2
Electronegativity 1.65 Pauling
Electron affinity —
First ionization energy 9.394 eV
Covalent 122 pm
van der Waals 210 pm
Ionic radii
Ion
CN
Radius / pm
Note
Zn+2
6
74
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
sphalerite and smithsonite
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: Ancient
Known and used before modern chemistry; recognition as an element belongs to the later development of the discipline.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 69.723 u
Electron configuration [Ar] 3d10 4s2 4p1
Standard state solid
Common oxidation states +3, +1
Electronegativity 1.81 Pauling
Electron affinity 0.3 eV
First ionization energy 5.999 eV
Covalent 122 pm
van der Waals 210 pm
Ionic radii
Ion
CN
Radius / pm
Note
Ga+3
6
62
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
p-block metal with moderate reactivity, multiple oxidation states and a growing inert-pair effect for heavier members.
Discovery and short history
Year / era: 1875
Identified in 1875, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 72.61 u
Electron configuration [Ar] 3d10 4s2 4p2
Standard state solid
Common oxidation states +4, +2
Electronegativity 2.01 Pauling
Electron affinity 1.35 eV
First ionization energy 7.9 eV
Covalent 120 pm
van der Waals 210 pm
Ionic radii
Ion
CN
Radius / pm
Note
Ge+4
6
53
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
intermediate metal/nonmetal behavior; covalent bonding and structure-dependent properties are common.
Discovery and short history
Year / era: 1886
Identified in 1886, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 74.922 u
Electron configuration [Ar] 3d10 4s2 4p3
Standard state solid
Common oxidation states +5, +3, −3
Electronegativity 2.18 Pauling
Electron affinity 0.81 eV
First ionization energy 9.815 eV
Covalent 119 pm
van der Waals 205 pm
Ionic radii
Ion
CN
Radius / pm
Note
As+3
6
58
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
forms covalent compounds and increasingly metallic species down the group; −3, +3 and +5 are important oxidation patterns.
Discovery and short history
Year / era: Ancient
Known and used before modern chemistry; recognition as an element belongs to the later development of the discipline.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 78.96 u
Electron configuration [Ar] 3d10 4s2 4p4
Standard state solid
Common oxidation states +6, +4, −2
Electronegativity 2.55 Pauling
Electron affinity 2.021 eV
First ionization energy 9.752 eV
Covalent 120 pm
van der Waals 190 pm
Ionic radii
Ion
CN
Radius / pm
Note
Se−2
6
198
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
forms chalcogenides and oxides; chemistry shifts from strongly oxidizing oxygen toward more metallic behavior down the group.
Discovery and short history
Year / era: 1817
Identified in 1817, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 79.904 u
Electron configuration [Ar] 3d10 4s2 4p5
Standard state liquid
Common oxidation states +7, +5, +3, +1, −1
Electronegativity 2.96 Pauling
Electron affinity 3.365 eV
First ionization energy 11.814 eV
Covalent 120 pm
van der Waals 190 pm
Ionic radii
Ion
CN
Radius / pm
Note
Br−1
6
196
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
strong tendency to form X⁻; typical oxidizing/halogenating chemistry, with reactivity generally decreasing down the group.
Discovery and short history
Year / era: 1826
Identified in 1826, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 83.8 u
Electron configuration [Ar] 3d10 4s2 4p6
Standard state gas
Common oxidation states 0, +2
Electronegativity 3 Pauling
Electron affinity —
First ionization energy 14 eV
Covalent 116 pm
van der Waals 202 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
trace constituent of the atmosphere or a product of radioactive decay
Typical reactivity
very low reactivity; heavier members, especially Xe and to a lesser extent Kr, form compounds under suitable conditions.
Discovery and short history
Year / era: 1898
Identified in 1898, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 85.468 u
Electron configuration [Kr] 5s1
Standard state solid
Common oxidation states +1
Electronegativity 0.82 Pauling
Electron affinity 0.468 eV
First ionization energy 4.177 eV
Covalent 220 pm
van der Waals 290 pm
Ionic radii
Ion
CN
Radius / pm
Note
Rb+1
6
152
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
red-violet
~780 / 795 nm prominent lines
Observed color depends on the volatile species and flame conditions; it is not the color of bulk elemental material.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
highly electropositive metal: rapidly oxidizes and reacts with water to form hydroxide and H₂; reactivity increases down the group.
Discovery and short history
Year / era: 1861
Identified in 1861, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 87.62 u
Electron configuration [Kr] 5s2
Standard state solid
Common oxidation states +2
Electronegativity 0.95 Pauling
Electron affinity —
First ionization energy 5.695 eV
Covalent 195 pm
van der Waals 255 pm
Ionic radii
Ion
CN
Radius / pm
Note
Sr+2
6
118
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
crimson / scarlet red
~606–674 nm line-rich emission
Observed color depends on the volatile species and flame conditions; it is not the color of bulk elemental material.
Occurrence and minerals
celestine and strontianite
Typical reactivity
electropositive metal; mainly forms M²⁺ and basic oxides/hydroxides. Water reactivity generally increases down the group.
Discovery and short history
Year / era: 1790
Identified in 1790, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 88.906 u
Electron configuration [Kr] 4d1 5s2
Standard state solid
Common oxidation states +3
Electronegativity 1.22 Pauling
Electron affinity 0.307 eV
First ionization energy 6.217 eV
Covalent 190 pm
van der Waals 240 pm
Ionic radii
Ion
CN
Radius / pm
Note
Y+3
6
90
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1794
Identified in 1794, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 91.224 u
Electron configuration [Kr] 4d2 5s2
Standard state solid
Common oxidation states +4
Electronegativity 1.33 Pauling
Electron affinity 0.426 eV
First ionization energy 6.634 eV
Covalent 175 pm
van der Waals 230 pm
Ionic radii
Ion
CN
Radius / pm
Note
Zr+4
6
72
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
zircon and baddeleyite
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1789
Identified in 1789, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 92.906 u
Electron configuration [Kr] 4d4 5s1
Standard state solid
Common oxidation states +5, +3
Electronegativity 1.6 Pauling
Electron affinity 0.893 eV
First ionization energy 6.759 eV
Covalent 164 pm
van der Waals 215 pm
Ionic radii
Ion
CN
Radius / pm
Note
Nb+5
6
64
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
pyrochlore and columbite–tantalite
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1801
Identified in 1801, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 95.94 u
Electron configuration [Kr] 4d5 5s1
Standard state solid
Common oxidation states +6, +5, +4, +3
Electronegativity 2.16 Pauling
Electron affinity 0.746 eV
First ionization energy 7.092 eV
Covalent 154 pm
van der Waals 210 pm
Ionic radii
Ion
CN
Radius / pm
Note
Mo+6
6
59
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
molybdenite and wulfenite
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1778
Identified in 1778, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 98 u
Electron configuration [Kr] 4d5 5s2
Standard state solid
Common oxidation states +7, +6, +4
Electronegativity 1.9 Pauling
Electron affinity 0.55 eV
First ionization energy 7.28 eV
Covalent 147 pm
van der Waals 205 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
no economically useful natural mineral; mainly produced artificially
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1937
Technetium was the first element to be artificially produced and conclusively identified, filling a gap in the periodic table.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 101.07 u
Electron configuration [Kr] 4d7 5s1
Standard state solid
Common oxidation states +8, +4, +3
Electronegativity 2.2 Pauling
Electron affinity 1.05 eV
First ionization energy 7.361 eV
Covalent 146 pm
van der Waals 205 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1844
Identified in 1844, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 102.906 u
Electron configuration [Kr] 4d8 5s1
Standard state solid
Common oxidation states +3, +1
Electronegativity 2.28 Pauling
Electron affinity 1.137 eV
First ionization energy 7.459 eV
Covalent 142 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1803
Identified in 1803, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 106.42 u
Electron configuration [Kr] 4d10
Standard state solid
Common oxidation states +4, +2, 0
Electronegativity 2.2 Pauling
Electron affinity 0.557 eV
First ionization energy 8.337 eV
Covalent 139 pm
van der Waals 205 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1803
Identified in 1803, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 107.868 u
Electron configuration [Kr] 4d10 5s1
Standard state solid
Common oxidation states +1
Electronegativity 1.93 Pauling
Electron affinity 1.302 eV
First ionization energy 7.576 eV
Covalent 145 pm
van der Waals 210 pm
Ionic radii
Ion
CN
Radius / pm
Note
Ag+1
6
115
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
acanthite, argentiferous galena, chlorargyrite and native silver
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: Ancient
Known since antiquity; it has been used as a precious, monetary and photographic metal.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 112.412 u
Electron configuration [Kr] 4d10 5s2
Standard state solid
Common oxidation states +2
Electronegativity 1.69 Pauling
Electron affinity —
First ionization energy 8.994 eV
Covalent 144 pm
van der Waals 220 pm
Ionic radii
Ion
CN
Radius / pm
Note
Cd+2
6
95
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1817
Identified in 1817, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 114.818 u
Electron configuration [Kr] 4d10 5s2 5p1
Standard state solid
Common oxidation states +3, +1
Electronegativity 1.78 Pauling
Electron affinity 0.3 eV
First ionization energy 5.786 eV
Covalent 142 pm
van der Waals 220 pm
Ionic radii
Ion
CN
Radius / pm
Note
In+3
6
80
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
p-block metal with moderate reactivity, multiple oxidation states and a growing inert-pair effect for heavier members.
Discovery and short history
Year / era: 1863
Identified in 1863, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 118.711 u
Electron configuration [Kr] 4d10 5s2 5p2
Standard state solid
Common oxidation states +4, +2
Electronegativity 1.96 Pauling
Electron affinity 1.2 eV
First ionization energy 7.344 eV
Covalent 139 pm
van der Waals 225 pm
Ionic radii
Ion
CN
Radius / pm
Note
Sn+4
6
69
Shannon
Sn+2
6
118
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
cassiterite
Typical reactivity
p-block metal with moderate reactivity, multiple oxidation states and a growing inert-pair effect for heavier members.
Discovery and short history
Year / era: Ancient
Known and used before modern chemistry; recognition as an element belongs to the later development of the discipline.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 121.76 u
Electron configuration [Kr] 4d10 5s2 5p3
Standard state solid
Common oxidation states +5, +3, −3
Electronegativity 2.05 Pauling
Electron affinity 1.07 eV
First ionization energy 8.64 eV
Covalent 139 pm
van der Waals 220 pm
Ionic radii
Ion
CN
Radius / pm
Note
Sb+3
6
76
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
stibnite
Typical reactivity
forms covalent compounds and increasingly metallic species down the group; −3, +3 and +5 are important oxidation patterns.
Discovery and short history
Year / era: Ancient
Known and used before modern chemistry; recognition as an element belongs to the later development of the discipline.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 127.6 u
Electron configuration [Kr] 4d10 5s2 5p4
Standard state solid
Common oxidation states +6, +4, −2
Electronegativity 2.1 Pauling
Electron affinity 1.971 eV
First ionization energy 9.01 eV
Covalent 138 pm
van der Waals 210 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
forms chalcogenides and oxides; chemistry shifts from strongly oxidizing oxygen toward more metallic behavior down the group.
Discovery and short history
Year / era: 1782
Identified in 1782, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 126.904 u
Electron configuration [Kr] 4d10 5s2 5p5
Standard state solid
Common oxidation states +7, +5, +3, +1, −1
Electronegativity 2.66 Pauling
Electron affinity 3.059 eV
First ionization energy 10.451 eV
Covalent 139 pm
van der Waals 210 pm
Ionic radii
Ion
CN
Radius / pm
Note
I−1
6
220
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
strong tendency to form X⁻; typical oxidizing/halogenating chemistry, with reactivity generally decreasing down the group.
Discovery and short history
Year / era: 1811
Identified in 1811, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 131.29 u
Electron configuration [Kr] 4d10 5s2 5p6
Standard state gas
Common oxidation states 0, +2, +4, +6, +8
Electronegativity 2.6 Pauling
Electron affinity —
First ionization energy 12.13 eV
Covalent 140 pm
van der Waals 216 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
trace constituent of the atmosphere or a product of radioactive decay
Typical reactivity
very low reactivity; heavier members, especially Xe and to a lesser extent Kr, form compounds under suitable conditions.
Discovery and short history
Year / era: 1898
Identified in 1898, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 132.905 u
Electron configuration [Xe] 6s1
Standard state solid
Common oxidation states +1
Electronegativity 0.79 Pauling
Electron affinity 0.472 eV
First ionization energy 3.894 eV
Covalent 244 pm
van der Waals 300 pm
Ionic radii
Ion
CN
Radius / pm
Note
Cs+1
6
167
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
blue-violet
~455 / 459 nm prominent lines
Observed color depends on the volatile species and flame conditions; it is not the color of bulk elemental material.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
highly electropositive metal: rapidly oxidizes and reacts with water to form hydroxide and H₂; reactivity increases down the group.
Discovery and short history
Year / era: 1860
Identified in 1860, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 137.328 u
Electron configuration [Xe] 6s2
Standard state solid
Common oxidation states +2
Electronegativity 0.89 Pauling
Electron affinity —
First ionization energy 5.212 eV
Covalent 215 pm
van der Waals 270 pm
Ionic radii
Ion
CN
Radius / pm
Note
Ba+2
6
135
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
apple green
~524–554 nm line-rich emission
Observed color depends on the volatile species and flame conditions; it is not the color of bulk elemental material.
Occurrence and minerals
barite and witherite
Typical reactivity
electropositive metal; mainly forms M²⁺ and basic oxides/hydroxides. Water reactivity generally increases down the group.
Discovery and short history
Year / era: 1808
Identified in 1808, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 138.906 u
Electron configuration [Xe] 5d1 6s2
Standard state solid
Common oxidation states +3
Electronegativity 1.1 Pauling
Electron affinity 0.5 eV
First ionization energy 5.577 eV
Covalent 207 pm
van der Waals 250 pm
Ionic radii
Ion
CN
Radius / pm
Note
La+3
6
103.2
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1839
Identified in 1839, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 140.116 u
Electron configuration [Xe] 4f1 5d1 6s2
Standard state solid
Common oxidation states +4, +3
Electronegativity 1.12 Pauling
Electron affinity 0.5 eV
First ionization energy 5.539 eV
Covalent 204 pm
van der Waals 248 pm
Ionic radii
Ion
CN
Radius / pm
Note
Ce+3
6
101
Shannon
Ce+4
6
87
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1803
Identified in 1803, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 140.908 u
Electron configuration [Xe] 4f3 6s2
Standard state solid
Common oxidation states +3
Electronegativity 1.13 Pauling
Electron affinity —
First ionization energy 5.464 eV
Covalent 203 pm
van der Waals 247 pm
Ionic radii
Ion
CN
Radius / pm
Note
Pr+3
6
99
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1885
Identified in 1885, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 144.24 u
Electron configuration [Xe] 4f4 6s2
Standard state solid
Common oxidation states +3
Electronegativity 1.14 Pauling
Electron affinity —
First ionization energy 5.525 eV
Covalent 201 pm
van der Waals 245 pm
Ionic radii
Ion
CN
Radius / pm
Note
Nd+3
6
98.3
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1885
Identified in 1885, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 145 u
Electron configuration [Xe] 4f5 6s2
Standard state solid
Common oxidation states +3
Electronegativity —
Electron affinity —
First ionization energy 5.55 eV
Covalent 199 pm
van der Waals 243 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1945
Promethium was identified among fission products and has no stable isotopes.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 150.36 u
Electron configuration [Xe] 4f6 6s2
Standard state solid
Common oxidation states +3, +2
Electronegativity 1.17 Pauling
Electron affinity —
First ionization energy 5.644 eV
Covalent 198 pm
van der Waals 242 pm
Ionic radii
Ion
CN
Radius / pm
Note
Sm+3
6
95.8
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1879
Identified in 1879, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 151.964 u
Electron configuration [Xe] 4f7 6s2
Standard state solid
Common oxidation states +3, +2
Electronegativity —
Electron affinity —
First ionization energy 5.67 eV
Covalent 198 pm
van der Waals 240 pm
Ionic radii
Ion
CN
Radius / pm
Note
Eu+3
6
94.7
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1901
Identified in 1901, as radioactivity, spectroscopy and atomic physics transformed element discovery.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 157.25 u
Electron configuration [Xe] 4f7 5d1 6s2
Standard state solid
Common oxidation states +3
Electronegativity 1.2 Pauling
Electron affinity —
First ionization energy 6.15 eV
Covalent 196 pm
van der Waals 238 pm
Ionic radii
Ion
CN
Radius / pm
Note
Gd+3
6
93.8
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1880
Identified in 1880, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 158.925 u
Electron configuration [Xe] 4f9 6s2
Standard state solid
Common oxidation states +3
Electronegativity —
Electron affinity —
First ionization energy 5.864 eV
Covalent 194 pm
van der Waals 237 pm
Ionic radii
Ion
CN
Radius / pm
Note
Tb+3
6
92.3
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1843
Identified in 1843, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 162.5 u
Electron configuration [Xe] 4f10 6s2
Standard state solid
Common oxidation states +3
Electronegativity 1.22 Pauling
Electron affinity —
First ionization energy 5.939 eV
Covalent 192 pm
van der Waals 235 pm
Ionic radii
Ion
CN
Radius / pm
Note
Dy+3
6
91.2
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1886
Identified in 1886, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 164.93 u
Electron configuration [Xe] 4f11 6s2
Standard state solid
Common oxidation states +3
Electronegativity 1.23 Pauling
Electron affinity —
First ionization energy 6.022 eV
Covalent 192 pm
van der Waals 233 pm
Ionic radii
Ion
CN
Radius / pm
Note
Ho+3
6
90.1
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1878
Identified in 1878, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 167.26 u
Electron configuration [Xe] 4f12 6s2
Standard state solid
Common oxidation states +3
Electronegativity 1.24 Pauling
Electron affinity —
First ionization energy 6.108 eV
Covalent 189 pm
van der Waals 232 pm
Ionic radii
Ion
CN
Radius / pm
Note
Er+3
6
89.0
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1843
Identified in 1843, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 168.934 u
Electron configuration [Xe] 4f13 6s2
Standard state solid
Common oxidation states +3
Electronegativity 1.25 Pauling
Electron affinity —
First ionization energy 6.184 eV
Covalent 190 pm
van der Waals 230 pm
Ionic radii
Ion
CN
Radius / pm
Note
Tm+3
6
88.0
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1879
Identified in 1879, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 173.04 u
Electron configuration [Xe] 4f14 6s2
Standard state solid
Common oxidation states +3, +2
Electronegativity —
Electron affinity —
First ionization energy 6.254 eV
Covalent 187 pm
van der Waals 228 pm
Ionic radii
Ion
CN
Radius / pm
Note
Yb+3
6
86.8
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1878
Identified in 1878, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 174.967 u
Electron configuration [Xe] 4f14 5d1 6s2
Standard state solid
Common oxidation states +3
Electronegativity 1.27 Pauling
Electron affinity —
First ionization energy 5.426 eV
Covalent 187 pm
van der Waals 227 pm
Ionic radii
Ion
CN
Radius / pm
Note
Lu+3
6
86.1
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, bastnäsite, xenotime and other rare-earth minerals
Typical reactivity
electropositive metal, usually dominated by +3; tarnishes in air and reacts with acids, often slowly with water.
Discovery and short history
Year / era: 1907
Identified in 1907, as radioactivity, spectroscopy and atomic physics transformed element discovery.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 178.49 u
Electron configuration [Xe] 4f14 5d2 6s2
Standard state solid
Common oxidation states +4
Electronegativity 1.3 Pauling
Electron affinity —
First ionization energy 6.825 eV
Covalent 175 pm
van der Waals 225 pm
Ionic radii
Ion
CN
Radius / pm
Note
Hf+4
6
71
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
almost always associated with zirconium in zircon
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1923
Identified in 1923, as radioactivity, spectroscopy and atomic physics transformed element discovery.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 180.948 u
Electron configuration [Xe] 4f14 5d3 6s2
Standard state solid
Common oxidation states +5
Electronegativity 1.5 Pauling
Electron affinity 0.322 eV
First ionization energy 7.89 eV
Covalent 170 pm
van der Waals 220 pm
Ionic radii
Ion
CN
Radius / pm
Note
Ta+5
6
64
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
tantalite and columbite–tantalite (coltan)
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1802
Identified in 1802, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 183.84 u
Electron configuration [Xe] 4f14 5d4 6s2
Standard state solid
Common oxidation states +6, +5, +4
Electronegativity 2.36 Pauling
Electron affinity 0.815 eV
First ionization energy 7.98 eV
Covalent 162 pm
van der Waals 210 pm
Ionic radii
Ion
CN
Radius / pm
Note
W+6
6
60
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
scheelite and wolframite
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1783
Identified in 1783, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 186.207 u
Electron configuration [Xe] 4f14 5d5 6s2
Standard state solid
Common oxidation states +7, +6, +4
Electronegativity 1.9 Pauling
Electron affinity 0.15 eV
First ionization energy 7.88 eV
Covalent 151 pm
van der Waals 205 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1925
Identified in 1925, as radioactivity, spectroscopy and atomic physics transformed element discovery.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 190.23 u
Electron configuration [Xe] 4f14 5d6 6s2
Standard state solid
Common oxidation states +8, +6, +4, +3
Electronegativity 2.2 Pauling
Electron affinity 1.1 eV
First ionization energy 8.7 eV
Covalent 144 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1803
Identified in 1803, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 192.217 u
Electron configuration [Xe] 4f14 5d7 6s2
Standard state solid
Common oxidation states +4, +3
Electronegativity 2.2 Pauling
Electron affinity 1.565 eV
First ionization energy 9.1 eV
Covalent 141 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1803
Identified in 1803, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 195.078 u
Electron configuration [Xe] 4f14 5d9 6s1
Standard state solid
Common oxidation states +4, +2
Electronegativity 2.28 Pauling
Electron affinity 2.128 eV
First ionization energy 9 eV
Covalent 136 pm
van der Waals 205 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
noble metal and major catalyst; highly corrosion-resistant.
Discovery and short history
Year / era: 1735
Identified in 1735, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 196.967 u
Electron configuration [Xe] 4f14 5d10 6s1
Standard state solid
Common oxidation states +3, +1
Electronegativity 2.54 Pauling
Electron affinity 2.309 eV
First ionization energy 9.226 eV
Covalent 136 pm
van der Waals 210 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
native gold and gold tellurides
Typical reactivity
noble metal, resistant to oxidation; reacts with aqua regia and suitable oxidizing/complexing systems.
Discovery and short history
Year / era: Ancient
Known since antiquity; low reactivity and occurrence as native metal favored its early use.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 200.59 u
Electron configuration [Xe] 4f14 5d10 6s2
Standard state liquid
Common oxidation states +2, +1
Electronegativity 2 Pauling
Electron affinity —
First ionization energy 10.438 eV
Covalent 132 pm
van der Waals 205 pm
Ionic radii
Ion
CN
Radius / pm
Note
Hg+2
6
102
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
cinnabar
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: Ancient
Known since antiquity, mercury is one of the few metallic elements liquid at room temperature.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 204.383 u
Electron configuration [Xe] 4f14 5d10 6s2 6p1
Standard state solid
Common oxidation states +3, +1
Electronegativity 1.62 Pauling
Electron affinity 0.2 eV
First ionization energy 6.108 eV
Covalent 145 pm
van der Waals 220 pm
Ionic radii
Ion
CN
Radius / pm
Note
Tl+1
6
150
Shannon
Tl+3
6
88.5
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
p-block metal with moderate reactivity, multiple oxidation states and a growing inert-pair effect for heavier members.
Discovery and short history
Year / era: 1861
Identified in 1861, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 207.2 u
Electron configuration [Xe] 4f14 5d10 6s2 6p2
Standard state solid
Common oxidation states +4, +2
Electronegativity 2.33 Pauling
Electron affinity 0.36 eV
First ionization energy 7.417 eV
Covalent 146 pm
van der Waals 230 pm
Ionic radii
Ion
CN
Radius / pm
Note
Pb+2
6
119
Shannon
Pb+4
6
77.5
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
galena, cerussite and anglesite
Typical reactivity
p-block metal with moderate reactivity, multiple oxidation states and a growing inert-pair effect for heavier members.
Discovery and short history
Year / era: Ancient
Known and used before modern chemistry; recognition as an element belongs to the later development of the discipline.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 208.98 u
Electron configuration [Xe] 4f14 5d10 6s2 6p3
Standard state solid
Common oxidation states +5, +3
Electronegativity 2.02 Pauling
Electron affinity 0.946 eV
First ionization energy 7.289 eV
Covalent 148 pm
van der Waals 230 pm
Ionic radii
Ion
CN
Radius / pm
Note
Bi+3
6
103
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
forms covalent compounds and increasingly metallic species down the group; −3, +3 and +5 are important oxidation patterns.
Discovery and short history
Year / era: 1753
Identified in 1753, during the early development of modern chemistry and chemical classification.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 209 u
Electron configuration [Xe] 4f14 5d10 6s2 6p4
Standard state solid
Common oxidation states +4, +2, −2
Electronegativity 2 Pauling
Electron affinity 1.9 eV
First ionization energy 8.417 eV
Covalent 140 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
forms chalcogenides and oxides; chemistry shifts from strongly oxidizing oxygen toward more metallic behavior down the group.
Discovery and short history
Year / era: 1898
Polonium was discovered during studies of uranium minerals and was among the first elements identified through radioactivity.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 210 u
Electron configuration [Xe] 4f14 5d10 6s2 6p5
Standard state solid (predicted; macroscopic samples unavailable)
Common oxidation states +7, +5, +3, +1, −1
Electronegativity 2.2 Pauling
Electron affinity 2.8 eV
First ionization energy 9.5 eV
Covalent 150 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
strong tendency to form X⁻; typical oxidizing/halogenating chemistry, with reactivity generally decreasing down the group.
Discovery and short history
Year / era: 1940
Identified in 1940 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 222 u
Electron configuration [Xe] 4f14 5d10 6s2 6p6
Standard state gas
Common oxidation states 0, +2
Electronegativity —
Electron affinity —
First ionization energy 10.745 eV
Covalent 150 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
trace constituent of the atmosphere or a product of radioactive decay
Typical reactivity
very low reactivity; heavier members, especially Xe and to a lesser extent Kr, form compounds under suitable conditions.
Discovery and short history
Year / era: 1900
Identified in 1900, as radioactivity, spectroscopy and atomic physics transformed element discovery.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 223 u
Electron configuration [Rn] 7s1
Standard state solid (predicted; macroscopic samples unavailable)
Common oxidation states +1
Electronegativity 0.7 Pauling
Electron affinity 0.47 eV
First ionization energy 3.9 eV
Covalent 260 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
highly electropositive metal: rapidly oxidizes and reacts with water to form hydroxide and H₂; reactivity increases down the group.
Discovery and short history
Year / era: 1939
Identified in 1939, as radioactivity, spectroscopy and atomic physics transformed element discovery.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 226 u
Electron configuration [Rn] 7s2
Standard state solid
Common oxidation states +2
Electronegativity 0.9 Pauling
Electron affinity —
First ionization energy 5.279 eV
Covalent 220 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
occurs in characteristic minerals or as a metallurgical by-product; see sources for detailed mineralogy
Typical reactivity
electropositive metal; mainly forms M²⁺ and basic oxides/hydroxides. Water reactivity generally increases down the group.
Discovery and short history
Year / era: 1898
Radium was isolated during the pioneering era of radioactivity and became important in the development of nuclear physics.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 227 u
Electron configuration [Rn] 6d1 7s2
Standard state solid
Common oxidation states +3
Electronegativity 1.1 Pauling
Electron affinity —
First ionization energy 5.17 eV
Covalent 215 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
mainly synthetic or present only in traces in natural radioactive decay chains
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1899
Identified in 1899, during the 19th-century expansion of spectroscopy and mineral chemistry.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 232.038 u
Electron configuration [Rn] 6d2 7s2
Standard state solid
Common oxidation states +4
Electronegativity 1.3 Pauling
Electron affinity —
First ionization energy 6.08 eV
Covalent 206 pm
van der Waals 240 pm
Ionic radii
Ion
CN
Radius / pm
Note
Th+4
6
94
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
monazite, thorite and thorianite
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1828
Identified in 1828, when mineral analysis and electrochemistry rapidly expanded the list of known elements.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 231.036 u
Electron configuration [Rn] 5f2 6d1 7s2
Standard state solid
Common oxidation states +5, +4
Electronegativity 1.5 Pauling
Electron affinity —
First ionization energy 5.89 eV
Covalent 200 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
mainly synthetic or present only in traces in natural radioactive decay chains
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1913
Identified in 1913, as radioactivity, spectroscopy and atomic physics transformed element discovery.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 238.029 u
Electron configuration [Rn] 5f3 6d1 7s2
Standard state solid
Common oxidation states +6, +5, +4, +3
Electronegativity 1.38 Pauling
Electron affinity —
First ionization energy 6.194 eV
Covalent 196 pm
van der Waals 230 pm
Ionic radii
Ion
CN
Radius / pm
Note
U+4
6
100
Shannon
U+6
6
73
Shannon
Selected Shannon effective ionic radii; values depend on coordination number and, for some ions, spin state.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
uraninite, carnotite, autunite and coffinite
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1789
Uranium was identified near the end of the 18th century; studies of its salts later led to the discovery of radioactivity.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 237 u
Electron configuration [Rn] 5f4 6d1 7s2
Standard state solid
Common oxidation states +6, +5, +4, +3
Electronegativity 1.36 Pauling
Electron affinity —
First ionization energy 6.266 eV
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
mainly synthetic or present only in traces in natural radioactive decay chains
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1940
Identified in 1940 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 244 u
Electron configuration [Rn] 5f6 7s2
Standard state solid
Common oxidation states +6, +5, +4, +3
Electronegativity 1.28 Pauling
Electron affinity —
First ionization energy 6.06 eV
Covalent 187 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
mainly synthetic or present only in traces in natural radioactive decay chains
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1940
Plutonium was produced and identified during the development of transuranium-element chemistry in the 20th century.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 243 u
Electron configuration [Rn] 5f7 7s2
Standard state solid
Common oxidation states +6, +5, +4, +3
Electronegativity 1.3 Pauling
Electron affinity —
First ionization energy 5.993 eV
Covalent 180 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic or available only in minute quantities; no exploitable mineral occurrence
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1944
Identified in 1944 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 247 u
Electron configuration [Rn] 5f7 6d1 7s2
Standard state solid
Common oxidation states +3
Electronegativity 1.3 Pauling
Electron affinity —
First ionization energy 6.02 eV
Covalent 169 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic or available only in minute quantities; no exploitable mineral occurrence
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1944
Identified in 1944 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 247 u
Electron configuration [Rn] 5f9 7s2
Standard state solid
Common oxidation states +4, +3
Electronegativity 1.3 Pauling
Electron affinity —
First ionization energy 6.23 eV
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic or available only in minute quantities; no exploitable mineral occurrence
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1949
Identified in 1949 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 251 u
Electron configuration [Rn] 5f10 7s2
Standard state solid
Common oxidation states +3
Electronegativity 1.3 Pauling
Electron affinity —
First ionization energy 6.3 eV
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic or available only in minute quantities; no exploitable mineral occurrence
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1950
Identified in 1950 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 252 u
Electron configuration [Rn] 5f11 7s2
Standard state solid
Common oxidation states +3
Electronegativity 1.3 Pauling
Electron affinity —
First ionization energy 6.42 eV
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic or available only in minute quantities; no exploitable mineral occurrence
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1952
Identified in 1952 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 257 u
Electron configuration [Rn] 5f12 7s2
Standard state solid
Common oxidation states +3
Electronegativity 1.3 Pauling
Electron affinity —
First ionization energy 6.5 eV
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic or available only in minute quantities; no exploitable mineral occurrence
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1952
Identified in 1952 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 258 u
Electron configuration [Rn] 5f13 7s2
Standard state solid
Common oxidation states +3, +2
Electronegativity 1.3 Pauling
Electron affinity —
First ionization energy 6.58 eV
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic or available only in minute quantities; no exploitable mineral occurrence
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1955
Identified in 1955 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 259 u
Electron configuration [Rn] 5f14 7s2
Standard state solid
Common oxidation states +3, +2
Electronegativity 1.3 Pauling
Electron affinity —
First ionization energy 6.65 eV
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic or available only in minute quantities; no exploitable mineral occurrence
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1958
Identified in 1958 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 262 u
Electron configuration [Rn] 5f14 7s2 7p1
Standard state solid
Common oxidation states +3
Electronegativity 1.3 Pauling
Electron affinity —
First ionization energy —
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic or available only in minute quantities; no exploitable mineral occurrence
Typical reactivity
radioactive metal; multiple oxidation states for early actinides, with important redox and complexation chemistry.
Discovery and short history
Year / era: 1961
Identified in 1961 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 267 u
Electron configuration [Rn] 5f14 6d2 7s2 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +4 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1964
Identified in 1964 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 268 u
Electron configuration [Rn] 5f14 6d3 7s2 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +5, +4, +3 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1967
Identified in 1967 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 269 u
Electron configuration [Rn] 5f14 6d4 7s2 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +6, +5, +4, +3 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1974
Identified in 1974 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 270 u
Electron configuration [Rn] 5f14 6d5 7s2 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +7, +5, +4, +3 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1981
Identified in 1981 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 269 u
Electron configuration [Rn] 5f14 6d6 7s2 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +8, +6, +4, +2 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1984
Identified in 1984 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 278 u
Electron configuration [Rn] 5f14 6d7 7s2 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +3, +1 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1982
Identified in 1982 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 281 u
Electron configuration [Rn] 5f14 6d9 7s1 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +6, +4, +2 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1994
Identified in 1994 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 281 u
Electron configuration [Rn] 5f14 6d10 7s1 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +3, +1 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1994
Identified in 1994 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 285 u
Electron configuration [Rn] 5f14 6d10 7s2 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +2, +1, 0 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 190 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
coordination chemistry and multiple oxidation states are common; reactivity and passivation depend strongly on element and environment.
Discovery and short history
Year / era: 1996
Identified in 1996 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 284 u
Electron configuration [Rn] 5f14 6d10 7s2 7p1 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +3, +1 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 136 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
p-block metal with moderate reactivity, multiple oxidation states and a growing inert-pair effect for heavier members.
Discovery and short history
Year / era: 2004
Identified in 2004 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 289 u
Electron configuration [Rn] 5f14 6d10 7s2 7p2 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +4, +2 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 143 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
p-block metal with moderate reactivity, multiple oxidation states and a growing inert-pair effect for heavier members.
Discovery and short history
Year / era: 1998
Identified in 1998 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 288 u
Electron configuration [Rn] 5f14 6d10 7s2 7p3 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +3, +1 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 162 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
forms covalent compounds and increasingly metallic species down the group; −3, +3 and +5 are important oxidation patterns.
Discovery and short history
Year / era: 2003
Identified in 2003 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 293 u
Electron configuration [Rn] 5f14 6d10 7s2 7p4 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +4, +2, −2 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 175 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
forms chalcogenides and oxides; chemistry shifts from strongly oxidizing oxygen toward more metallic behavior down the group.
Discovery and short history
Year / era: 2000
Identified in 2000 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 292 u
Electron configuration [Rn] 5f14 6d10 7s2 7p5 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states +5, +3, +1, −1 (pred.)
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 165 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
strong tendency to form X⁻; typical oxidizing/halogenating chemistry, with reactivity generally decreasing down the group.
Discovery and short history
Year / era: 2010
Identified in 2010 in the nuclear-chemistry era; very heavy elements are produced and identified through nuclear reactions and instrumental methods.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
Core properties
Atomic mass 294 u
Electron configuration [Rn] 5f14 6d10 7s2 7p6 predicted
Standard state not experimentally established; macroscopic state is predicted
Common oxidation states 0; altri stati predetti
Electronegativity —
Electron affinity —
First ionization energy —
Covalent 157 pm
van der Waals 200 pm
Ionic radii
No value is included in the selected teaching subset. Ionic radius requires a defined oxidation state and coordination environment.
Flame test
No common diagnostic classroom flame test is listed for this element.
Occurrence and minerals
synthetic superheavy element; produced atom by atom in accelerator experiments
Typical reactivity
very low reactivity; heavier members, especially Xe and to a lesser extent Kr, form compounds under suitable conditions.
Discovery and short history
Year / era: 2006
Oganesson is a superheavy element produced atom by atom; much of its chemistry remains theoretical and predicted.
How to read these data
Electronegativity is on the Pauling scale. Atomic radius is not unique: a reference covalent radius and van der Waals radius are shown here. Ionic radii, where listed, are selected Shannon values and must be read together with oxidation state, coordination number and sometimes spin. For superheavy elements, many macroscopic and electronic properties are predicted rather than directly measured.
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