Argon vs Actinium
| Property | Ar Argon | Ac Actinium |
|---|---|---|
| Atomic number | 18 | 89 |
| Symbol | Ar | Ac |
| Name | Argon | Actinium |
| Category | noble-gas | actinide |
| Standard Atomic Weight | 39.948 u | 227 u |
| Period | 3 | 7 |
| Group | 18 | N/A |
| Block | p | s |
| Phase at STP | gas | solid |
| Electron configuration | [Ne]3s23p6 | [Rn]7s26d1 |
| Oxidation states | [0] | [3] |
| Electronegativity (Pauling) | N/A | 1.1 |
| Electron affinity | -1 eV | 0.35 eV |
| Density | 1.7837 kg/m³ | 1.007000e+4 kg/m³ |
| Melting point | -189.35 °C | 1050.85 °C |
| Boiling point | -185.85 °C | 3197.85 °C |
| Discovery year | 1894 | 1899 |