Cesium vs Actinium
| Property | Cs Cesium | Ac Actinium |
|---|---|---|
| Atomic number | 55 | 89 |
| Symbol | Cs | Ac |
| Name | Cesium | Actinium |
| Category | alkali-metal | actinide |
| Standard Atomic Weight | 132.905452 u | 227 u |
| Period | 6 | 7 |
| Group | 1 | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Xe]6s1 | [Rn]7s26d1 |
| Oxidation states | [-1, 1] | [3] |
| Electronegativity (Pauling) | 0.79 | 1.1 |
| Electron affinity | 0.4716 eV | 0.35 eV |
| Density | 1930 kg/m³ | 1.007000e+4 kg/m³ |
| Melting point | 28.44 °C | 1050.85 °C |
| Boiling point | 670.85 °C | 3197.85 °C |
| Discovery year | 1860 | 1899 |