34
Se
78.971
Selenium
Element 34 · 78.971 u · p-block
nonmetal
An essential trace element. Used in glass-making, photocells, and as a dietary supplement.
Phase (STP)
Solid
Melting Point
221 °C
Boiling Point
685 °C
Density
4.809 g/cm³
Electronegativity
2.55
Atomic Radius
115 pm
Ionization Energy
941 kJ/mol
Electron Affinity
195 kJ/mol
Discovered
1817 · Jons Jacob Berzelius
Electron Configuration
[Ar] 3d10 4s2 4p4
Electron Orbitals
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