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34 - Selenium polyatomic nonmetal

Discovered by Jöns Berzelius in 1817

Selenium

Selenium is a chemical element with symbol Se and atomic number 34. It is a nonmetal with properties that are intermediate between those of its periodic table column-adjacent chalcogen elements sulfur and tellurium. It rarely occurs in its elemental state in nature, or as pure ore compounds.
Shell Electrons Orbitals
1 2 2 in 1s
2 8 2 in 2s + 6 in 2p
3 18 2 in 3s + 6 in 3p + 10 in 3d
4 6 2 in 4s + 4 in 4p
SeleniumSe Electron 1 Electron 2 Electron 1 Electron 2 Electron 3 Electron 4 Electron 5 Electron 6 Electron 7 Electron 8 Electron 1 Electron 2 Electron 3 Electron 4 Electron 5 Electron 6 Electron 7 Electron 8 Electron 9 Electron 10 Electron 11 Electron 12 Electron 13 Electron 14 Electron 15 Electron 16 Electron 17 Electron 18 Electron 1 Electron 2 Electron 3 Electron 4 Electron 5 Electron 6
78.97  u Atomic Mass
1.2  Å Atomic Radius
958  K Boiling Point
1.2  Å Covalent Radius
4.81  g/cm³ Density
194.96 Electron Affinity
2.55 Electronegativity
9.75  eV First Ionization Energy
494.15  K Melting Point
4 Number of Shells
6 Electron Valency
34 Atomic Number
2, 8, 18, 6 Electron Shell Occupations
0.32  J/(g K) Specific Heat