Se
Selenium
Z 34 78.971 g/molOther Nonmetal
Nucleus
34 Protons
45 Neutrons
34 Electrons (6 Valence)
Shell distribution: K2 • L8 • M18 • N6 • O0 • P0 • Q0
Electron Configuration
Energy
7p
6d
5f
7s
6p
5d
4f
6s
5p
4d
5s
4p
3d
4s
3p
3s
2p
2s
1s
[Ar]3d104s24p4
Oxidation States
CommonRare
0
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Radii
Empirical
115 pm1.15 Å
Calculated
103 pm1.03 Å
Covalent
120±4 pm1.2±0.04 Å
Van der Waals
190 pm1.9 Å
IonicSe2-
198 pm1.98 Å
Crystal Structure
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HexagonalStandard state
Pearson symbol
hP3
Space group
P3121 No. 152
Density
4.81 g/cm³