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Selenium

Non-Metalsolid
Symbol: Se
Atomic number: 34
Atomic mass: 78.96
Group: Non-Metal
CAS-number: 7782-49-2

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Physical data
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Physical data

Electronic dataThermal dataSteric data
Shells: 2, 8, 18, 6
Orbitals: [Ar] 3d10 4s2 4p4
Electronegativity: 2.4, 2.5
1. Ionization potential: 9.7524 eV
2. Ionization potential: 21.19 eV
3. Ionization potential: 30.82 eV
Oxidation states: 6, 4, -2
Electrical conductivity: 1.0e-12 10^6
Melting point: 217 °C
Boiling point: 684.9 °C
Specific heat: 0.32 J/gK
Heat of fusion: 6.694 kJ/mol
Heat of vaporization: 37.70 kJ/mol
Thermal conductivity: 0.0204 W/cmK
Atomic radius: 1.22 Å
Ionic radius: 0.50 Å (+4)
Covalent radius: 1.16 Å
Atomic volume: 16.45 cm³/mol
Density (293 K): 4.79 g/cm³
Crystal structure: hexagonal
hexagonal

Isotopes

NuclideAbundance [%]MassSpinHalflifeDecay modeDecay tree
73Se 0 73 0 7.15h β- View
74Se 0.87 73.9225 0 -- --
75Se 0 74.923 0 119.78d β- View
76Se 9.02 75.9192 0 -- --
77Se 7.58 76.9199 1/2 -- --
78Se 23.52 77.9173 0 -- --
79Se 0 78.919 7/2 ~6.5E04y β- View
80Se 49.82 79.9165 0 -- --
82Se 9.19 81.9167 0 -- --

Other info

Name origin:Greek: selênê (moon)
Description:Soft metalloid similar to sulfur. Ranges from gray metallic to red glassy appearance.
Discovered by:Jöns Berzelius
Year:1818
Place:Sweden
Sources:Obtained from lead, copper and nickel refining. Conducts electricity when struck by light.
Use(s):Light causes it to conduct electricity more easily. It is used in photoelectric cells, TV cameras, xerography machines and as a semiconductor in solar batteries and rectifiers. Also colors glass red.