34 Se
Reactive nonmetal
Selenium
Used in solar cells.
Properties of Selenium
- Atomic number (Z)
- 34
- Symbol
- Se
- Atomic mass
- 78.971 g/mol
- Category
- Reactive nonmetal
- Group
- 16
- Period
- 4
- Electron configuration
- [Ar] 3d¹⁰ 4s² 4p⁴
- Electronegativity (Pauling)
- 2.55
- Atomic radius
- 103 pm
- First ionization energy
- 941 kJ/mol
- Melting point
- 453 K (179.9 °C)
- Boiling point
- 958 K (684.9 °C)
- Density
- 4.809 g/cm³
- Phase at 25 °C
- Solid
- Discovered
- Discovered in 1817