Oxygen (O)
Element 8 Ā· Reactive nonmetal
Oxygen (O) is a chemical element with atomic number 8. It is classified as a reactive nonmetal in period 2, group 16 of the periodic table (the p-block). Its standard atomic weight is 15.999 u and its ground-state electron configuration is [He] 2sĀ² 2pā“.
Oxygen facts
| Atomic number (Z) | 8 |
|---|---|
| Symbol | O |
| Standard atomic weight | 15.999 u |
| Category | Reactive nonmetal |
| Group | 16 |
| Period | 2 |
| Block | p-block |
| Electron configuration | [He] 2sĀ² 2pā“ |
| Electronegativity (Pauling) | 3.44 |
| State at 20 Ā°C | Gas |
| Protons / electrons | 8 / 8 |
| Neutrons (most common isotope, approx.) | 8 |
| Molar mass | 15.999 g/mol |