Oxygen vs Argon
| Property | O Oxygen | Ar Argon |
|---|---|---|
| Atomic number | 8 | 18 |
| Symbol | O | Ar |
| Name | Oxygen | Argon |
| Category | nonmetal | noble-gas |
| Standard Atomic Weight | 15.9994 u | 39.948 u |
| Period | 2 | 3 |
| Group | 16 | 18 |
| Block | p | p |
| Phase at STP | gas | gas |
| Electron configuration | [He]2s22p4 | [Ne]3s23p6 |
| Oxidation states | [-2, -1, 0, 1, 2] | [0] |
| Electronegativity (Pauling) | 3.44 | N/A |
| Electron affinity | 1.4611 eV | -1 eV |
| Density | 1.429 kg/m³ | 1.7837 kg/m³ |
| Melting point | -218.79 °C | -189.35 °C |
| Boiling point | -182.95 °C | -185.85 °C |
| Discovery year | 1771 | 1894 |