Rubidium vs Fermium
| Property | Rb Rubidium | Fm Fermium |
|---|---|---|
| Atomic number | 37 | 100 |
| Symbol | Rb | Fm |
| Name | Rubidium | Fermium |
| Category | alkali-metal | actinide |
| Standard Atomic Weight | 85.4678 u | 257 u |
| Period | 5 | 7 |
| Group | 1 | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Kr]5s1 | [Rn] 5f12 7s2 |
| Oxidation states | [-1, 1] | [2, 3] |
| Electronegativity (Pauling) | 0.82 | 1.3 |
| Electron affinity | 0.4859 eV | 0.339 eV |
| Density | 1530 kg/m³ | 9700 kg/m³ |
| Melting point | 39.31 °C | 1526.85 °C |
| Boiling point | 687.85 °C | -273.15 °C |
| Discovery year | 1861 | 1952 |