Oxygen (O)
Oxygenium
Oxygen (O) is a non-metal in period 2, group 16. Its relative atomic mass is 15.999 and the molar mass of the atom is 15.999 g/mol; the molar mass of O₂ is 31.998 g/mol.
Atomic number 8
Atomic mass 15.999
Molar mass 15.999 g/mol O₂: 31.998 g/mol
Category Non-metal Gas
Properties of oxygen
| Atomic number | 8 |
|---|---|
| Symbol | O |
| Latin name | Oxygenium |
| Relative atomic mass | 15.999 |
| Molar mass | 15.999 g/mol · O₂: 31.998 g/mol |
| Group, period, block | 16, 2, p |
| Category | Non-metal |
| State at 20 °C | Gas |
| Electron configuration | [He] 2s² 2p⁴ |
| Electronegativity (Pauling) | 3.44 |
| Atomic radius | 60 pm |
Electron configuration of oxygen
Electrons per shell
K2L6
Full notation
1s² 2s² 2p⁴
Noble-gas notation
8 protons · 8 electrons[He] 2s² 2p⁴
Formula and compounds of oxygen
Simple substanceO₂oxygenMolar mass of O₂: 31.998 g/mol
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Frequently asked questions
The relative atomic mass of oxygen is 15.999, so the molar mass of the atom is 15.999 g/mol; the molar mass of O₂ is 31.998 g/mol.
Full: 1s² 2s² 2p⁴. Noble-gas notation: [He] 2s² 2p⁴.