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18
Ar
39.948
Argon
Noble gases · Group 18 · Period 3
Atomic properties
| Atomic number | 18 |
|---|---|
| Symbol | Ar |
| Standard atomic weight | 39.948 |
| Classification | Noble gases |
| Group | 18 |
| Period | 3 |
| Block | p-block |
| Electron configuration | [Ne] 3s2 3p6 |
| Electronegativity (Pauling) | — |
| Common oxidation states | 0 |
Physical properties
| Phase at 20 °C | Gas |
|---|---|
| Density | 0.001784 g/cm³ |
| Melting point | -189.34 °C |
| Boiling point | -185.85 °C |
| Discovered | 1894 |
| CAS number | — |