Atomic Number | 34 |
---|---|
Atomic Weight | 78.971 |
Mass Number | 80 |
Group | 16 |
---|---|
Period | 4 |
Block | p |
Protons | 34 p+ |
---|---|
Neutrons | 46 n0 |
Electrons | 34 e- |
Atomic Radius | 115 pm
|
---|---|
Molar Volume | 16.5 cm³/mol
|
Covalent Radius | 116 pm
|
Metallic Radius | 117 pm
|
Ionic Radius | 198 pm
|
Crystal Radius | 184 pm
|
Van der Waals Radius | 190 pm
|
Density | 4.809 g/cm³
|
Energy | |
Proton Affinity | |
Electron Affinity | 2.02067 eV/particle
|
Ionization Energy | 9.752392 eV/particle
|
Heat of Vaporization | 59.7 kJ/mol
|
Heat of Fusion | 5.23 kJ/mol
|
Heat of Formation | 227.2 kJ/mol
|
Electrons | |
Electron Shells | 2, 8, 18, 6 |
Valence Electrons | 6 |
Electron Configuration | [Ar] 3d10 4s2 4p4 |
Oxidation States | -2, -1, 0, 1, 2, 3, 4, 5, 6 |
Electronegativity | 2.55
|
Electrophilicity | 2.2408492709619536 eV/particle
|
Phases | |
Phase | Solid |
Gas Phase | |
Boiling Point | 958.15 K
|
Melting Point | 453.15 K
|
Critical Pressure | |
Critical Temperature | 1,766.15 K
|
Triple Point | |
Visual | |
Color | Gray
|
Appearance | black, red, and gray (not pictured) allotropes |
Refractive Index | 1.000895
|
Thermodynamic Properties | |
Thermal Conductivity | 0.52 W/(m K)
|
Thermal Expansion | |
Molar Heat Capacity | 25.363 J/(mol K)
|
Specific Heat Capacity | 0.321 J/(g⋅K)
|
Heat Capacity Ratio (Adiabatic Index) | |
Electrical Properties | |
Type | |
Electrical Conductivity | |
Electrical Resistivity | |
Superconducting Point | |
Magnetism | |
Type | diamagnetic |
Magnetic Susceptibility (Mass) | -0.000000004 m³/Kg
|
Magnetic Susceptibility (Molar) | -0.000000000316 m³/mol
|
Magnetic Susceptibility (Volume) | -0.0000193
|
Magnetic Ordering | |
Curie Point | |
Neel Point | |
Structure | |
Crystal Structure | Simple Monoclinic (HEX) |
Lattice Constant | 4.36 Å
|
Lattice Angles | π/2, 1.58493, π/2 |
Mechanical Properties | |
Hardness | 2 MPa
|
Bulk Modulus | 8.3 GPa
|
Shear Modulus | 3.7 GPa
|
Young Modulus | 10 GPa
|
Poisson Ratio | 0.33
|
Speed of Sound | 3,350 m/s
|
Classification | |
Category | Other nonmetals, Nonmetals |
CAS Group | VIB |
IUPAC Group | VIA |
Glawe Number | 95 |
Mendeleev Number | 101 |
Pettifor Number | 93 |
Geochemical Class | semi-volatile |
Goldschmidt Class | chalcophile |
Other | |
Gas Basicity | |
Dipole Polarizability | |
C6 Dispersion Coefficient | 210 a₀
|
Allotropes | Amorphous Red Selenium, Amorphous Black Selenium, Monoclinic Selenium, Hexagonal Selenium |
Neutron Cross Section | 11.7
|
Neutron Mass Absorption | 0.0056
|
Quantum Numbers | 3P2 |
Space Group | 14 (P121/c1) |
Stable Isotopes | 6 |
---|---|
Unstable Isotopes | 27 |
Radioactive Isotopes | 28 |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 63 |
G-Factor | |
Half Life | 13.2 ± 3.9 ms
|
Spin | 3/2 |
Quadrupole Moment | |
Discovery Year | 2016 |
Parity | - |
Decay Mode | Intensity |
---|---|
β+ (β+ decay; β+ = ϵ + e+) | 100% |
β+ p (β+-delayed proton emission) | 89% |
2p (2-proton emission) | 0.5% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 64 |
G-Factor | 0
|
Half Life | 22.6 ± 0.2 ms
|
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 2005 |
Parity | + |
Decay Mode | Intensity |
---|---|
β+ (β+ decay; β+ = ϵ + e+) | % |
β+ p (β+-delayed proton emission) | % |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 65 |
G-Factor | |
Half Life | 34.2 ± 0.7 ms
|
Spin | 3/2 |
Quadrupole Moment | |
Discovery Year | 1993 |
Parity | - |
Decay Mode | Intensity |
---|---|
β+ (β+ decay; β+ = ϵ + e+) | 100% |
β+ p (β+-delayed proton emission) | 87% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 66 |
G-Factor | 0
|
Half Life | 54 ± 4 ms
|
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1993 |
Parity | + |
Decay Mode | Intensity |
---|---|
β+ (β+ decay; β+ = ϵ + e+) | 100% |
β+ p (β+-delayed proton emission) | % |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 67 |
G-Factor | |
Half Life | 133 ± 4 ms
|
Spin | 5/2 |
Quadrupole Moment | |
Discovery Year | 1991 |
Parity | - |
Decay Mode | Intensity |
---|---|
β+ (β+ decay; β+ = ϵ + e+) | 100% |
β+ p (β+-delayed proton emission) | 0.5% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 68 |
G-Factor | 0
|
Half Life | 35.5 ± 0.7 s
|
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1990 |
Parity | + |
Decay Mode | Intensity |
---|---|
β+ (β+ decay; β+ = ϵ + e+) | 100% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 69 |
G-Factor | |
Half Life | 27.4 ± 0.2 s
|
Spin | 1/2 |
Quadrupole Moment | 0
|
Discovery Year | 1974 |
Parity | - |
Decay Mode | Intensity |
---|---|
β+ (β+ decay; β+ = ϵ + e+) | 100% |
β+ p (β+-delayed proton emission) | 0.052% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 70 |
G-Factor | 0
|
Half Life | 41.1 ± 0.3 m
|
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1950 |
Parity | + |
Decay Mode | Intensity |
---|---|
β+ (β+ decay; β+ = ϵ + e+) | 100% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 71 |
G-Factor | |
Half Life | 4.74 ± 0.05 m
|
Spin | 5/2 |
Quadrupole Moment | |
Discovery Year | 1957 |
Parity | - |
Decay Mode | Intensity |
---|---|
β+ (β+ decay; β+ = ϵ + e+) | 100% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 72 |
G-Factor | 0
|
Half Life | 8.4 ± 0.08 d
|
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1948 |
Parity | + |
Decay Mode | Intensity |
---|---|
ϵ (electron capture) | 100% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 73 |
G-Factor | 0.19822222222222 ± 0.0028888888888889
|
Half Life | 7.15 ± 0.09 h
|
Spin | 9/2 |
Quadrupole Moment | |
Discovery Year | 1948 |
Parity | + |
Decay Mode | Intensity |
---|---|
β+ (β+ decay; β+ = ϵ + e+) | 100% |
Abundance | 0.86 ± 0.03
|
---|---|
Relative Atomic Mass | |
Mass Number | 74 |
G-Factor | 0
|
Half Life | |
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1922 |
Parity | + |
Decay Mode | Intensity |
---|---|
2β+ (double β+ decay) | % |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 75 |
G-Factor | 0.2732 ± 0.004
|
Half Life | 119.78 ± 0.03 d
|
Spin | 5/2 |
Quadrupole Moment | 1.1 ± 0.2
|
Discovery Year | 1947 |
Parity | + |
Decay Mode | Intensity |
---|---|
ϵ (electron capture) | 100% |
Abundance | 9.23 ± 0.07
|
---|---|
Relative Atomic Mass | |
Mass Number | 76 |
G-Factor | 0
|
Half Life | |
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1922 |
Parity | + |
Abundance | 7.6 ± 0.07
|
---|---|
Relative Atomic Mass | |
Mass Number | 77 |
G-Factor | 1.06712 ± 0.0001
|
Half Life | |
Spin | 1/2 |
Quadrupole Moment | 0
|
Discovery Year | 1922 |
Parity | - |
Abundance | 23.69 ± 0.22
|
---|---|
Relative Atomic Mass | |
Mass Number | 78 |
G-Factor | 0
|
Half Life | |
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1922 |
Parity | + |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 79 |
G-Factor | -0.29085714285714 ± 0.0042857142857143
|
Half Life | 327 ± 28 ky
|
Spin | 7/2 |
Quadrupole Moment | 0.8 ± 0.2
|
Discovery Year | 1950 |
Parity | + |
Decay Mode | Intensity |
---|---|
β− (β− decay) | 100% |
Abundance | 49.8 ± 0.36
|
---|---|
Relative Atomic Mass | |
Mass Number | 80 |
G-Factor | 0
|
Half Life | |
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1922 |
Parity | + |
Decay Mode | Intensity |
---|---|
2β− (double β− decay) | % |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 81 |
G-Factor | |
Half Life | 18.45 ± 0.12 m
|
Spin | 1/2 |
Quadrupole Moment | 0
|
Discovery Year | 1948 |
Parity | - |
Decay Mode | Intensity |
---|---|
β− (β− decay) | 100% |
Abundance | Radioactive ☢️ 8.82 ± 0.15
|
---|---|
Relative Atomic Mass | |
Mass Number | 82 |
G-Factor | 0
|
Half Life | 87.6 ± 1.5 Ey
|
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1922 |
Parity | + |
Decay Mode | Intensity |
---|---|
2β− (double β− decay) | 100% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 83 |
G-Factor | |
Half Life | 22.25 ± 0.04 m
|
Spin | 9/2 |
Quadrupole Moment | |
Discovery Year | 1937 |
Parity | + |
Decay Mode | Intensity |
---|---|
β− (β− decay) | 100% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 84 |
G-Factor | 0
|
Half Life | 3.26 ± 0.1 m
|
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1960 |
Parity | + |
Decay Mode | Intensity |
---|---|
β− (β− decay) | 100% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 85 |
G-Factor | |
Half Life | 32.9 ± 0.3 s
|
Spin | 5/2 |
Quadrupole Moment | |
Discovery Year | 1960 |
Parity |
Decay Mode | Intensity |
---|---|
β− (β− decay) | 100% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 86 |
G-Factor | 0
|
Half Life | 14.3 ± 0.3 s
|
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1973 |
Parity | + |
Decay Mode | Intensity |
---|---|
β− (β− decay) | 100% |
β− n (β−-delayed neutron emission) | % |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 87 |
G-Factor | |
Half Life | 5.5 ± 0.06 s
|
Spin | 3/2 |
Quadrupole Moment | |
Discovery Year | 1968 |
Parity | + |
Decay Mode | Intensity |
---|---|
β− (β− decay) | 100% |
β− n (β−-delayed neutron emission) | 0.6% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 88 |
G-Factor | 0
|
Half Life | 1.53 ± 0.06 s
|
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1970 |
Parity | + |
Decay Mode | Intensity |
---|---|
β− (β− decay) | 100% |
β− n (β−-delayed neutron emission) | 0.99% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 89 |
G-Factor | |
Half Life | 430 ± 50 ms
|
Spin | 5/2 |
Quadrupole Moment | |
Discovery Year | 1971 |
Parity | + |
Decay Mode | Intensity |
---|---|
β− (β− decay) | 100% |
β− n (β−-delayed neutron emission) | 7.8% |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 90 |
G-Factor | 0
|
Half Life | 210 ± 80 ms
|
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1994 |
Parity | + |
Decay Mode | Intensity |
---|---|
β− (β− decay) | 100% |
β− n (β−-delayed neutron emission) | % |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 91 |
G-Factor | |
Half Life | 270 ± 50 ms
|
Spin | 1/2 |
Quadrupole Moment | 0
|
Discovery Year | 1975 |
Parity | + |
Decay Mode | Intensity |
---|---|
β− (β− decay) | 100% |
β− n (β−-delayed neutron emission) | 21% |
2n (2-neutron emission) | % |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 92 |
G-Factor | 0
|
Half Life | |
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1997 |
Parity | + |
Decay Mode | Intensity |
---|---|
β− (β− decay) | % |
β− n (β−-delayed neutron emission) | % |
2n (2-neutron emission) | % |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 93 |
G-Factor | |
Half Life | |
Spin | 1/2 |
Quadrupole Moment | 0
|
Discovery Year | 1997 |
Parity | + |
Decay Mode | Intensity |
---|---|
β− (β− decay) | % |
β− n (β−-delayed neutron emission) | % |
2n (2-neutron emission) | % |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 94 |
G-Factor | 0
|
Half Life | |
Spin | 0 |
Quadrupole Moment | 0
|
Discovery Year | 1997 |
Parity | + |
Decay Mode | Intensity |
---|---|
β− (β− decay) | % |
β− n (β−-delayed neutron emission) | % |
2n (2-neutron emission) | % |
Abundance | Radioactive ☢️ |
---|---|
Relative Atomic Mass | |
Mass Number | 95 |
G-Factor | |
Half Life | |
Spin | 3/2 |
Quadrupole Moment | |
Discovery Year | 2010 |
Parity | + |
Decay Mode | Intensity |
---|---|
β− (β− decay) | % |
β− n (β−-delayed neutron emission) | % |
2n (2-neutron emission) | % |
Selenium was first observed in about the year 1300 by the alchemist Arnold of Villanova. Selenium was discovered in 1817 by Jöns Jacob Berzelius and Johan Gottlieb Gahn who noted the similarity of the new element to the previously-known tellurium. In 1873, Willoughby Smith found that the electrical resistance of grey selenium was dependent on the ambient light. From the Greek word Selene, moon
Discoverers | Jöns Berzelius |
---|---|
Discovery Location | Sweden |
Discovery Year | 1818 |
Etymology (Name Origin) | Greek: selênê (moon). |
Pronunciation | si-LEE-ni-em (English) |
1 | s | 0.7378 |
2 | p | 3.9348 |
2 | s | 9.1116 |
3 | d | 15.523 |
3 | p | 15.295 |
3 | s | 14.5966 |
4 | p | 25.7128 |
4 | s | 24.2424 |