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Oxygen
Reactive nonmetals · Group 16 · Period 2
Atomic properties
| Atomic number | 8 |
|---|---|
| Symbol | O |
| Standard atomic weight | 15.999 |
| Classification | Reactive nonmetals |
| Group | 16 |
| Period | 2 |
| Block | p-block |
| Electron configuration | [He] 2s2 2p4 |
| Electronegativity (Pauling) | 3.44 |
| Common oxidation states | -2 |
Physical properties
| Phase at 20 °C | Gas |
|---|---|
| Density | 0.001429 g/cm³ |
| Melting point | -218.79 °C |
| Boiling point | -182.96 °C |
| Discovered | 1774 |
| CAS number | — |