Selenium (Se)
Selenium
Selenium (Se) is a non-metal in period 4, group 16. Its relative atomic mass is 78.971 and the molar mass of the atom is 78.971 g/mol.
Atomic number 34
Atomic mass 78.971
Molar mass 78.971 g/mol
Category Non-metal Solid
Properties of selenium
| Atomic number | 34 |
|---|---|
| Symbol | Se |
| Latin name | Selenium |
| Relative atomic mass | 78.971 |
| Molar mass | 78.971 g/mol |
| Group, period, block | 16, 4, p |
| Category | Non-metal |
| State at 20 °C | Solid |
| Electron configuration | [Ar] 3d¹⁰ 4s² 4p⁴ |
| Electronegativity (Pauling) | 2.55 |
| Atomic radius | 115 pm |
Electron configuration of selenium
Electrons per shell
K2L8M18N6
Full notation
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁴
Noble-gas notation
34 protons · 34 electrons[Ar] 3d¹⁰ 4s² 4p⁴
Formula and compounds of selenium
Simple substanceSeseleniumMolar mass of Se: 78.971 g/mol
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Frequently asked questions
The relative atomic mass of selenium is 78.971, so the molar mass of the atom is 78.971 g/mol.
Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁴. Noble-gas notation: [Ar] 3d¹⁰ 4s² 4p⁴.