Rubidium vs Cesium
| Property | Rb Rubidium | Cs Cesium |
|---|---|---|
| Atomic number | 37 | 55 |
| Symbol | Rb | Cs |
| Name | Rubidium | Cesium |
| Category | alkali-metal | alkali-metal |
| Standard Atomic Weight | 85.4678 u | 132.905452 u |
| Period | 5 | 6 |
| Group | 1 | 1 |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Kr]5s1 | [Xe]6s1 |
| Oxidation states | [-1, 1] | [-1, 1] |
| Electronegativity (Pauling) | 0.82 | 0.79 |
| Electron affinity | 0.4859 eV | 0.4716 eV |
| Density | 1530 kg/m³ | 1930 kg/m³ |
| Melting point | 39.31 °C | 28.44 °C |
| Boiling point | 687.85 °C | 670.85 °C |
| Discovery year | 1861 | 1860 |