Actinium vs Fermium
| Property | Ac Actinium | Fm Fermium |
|---|---|---|
| Atomic number | 89 | 100 |
| Symbol | Ac | Fm |
| Name | Actinium | Fermium |
| Category | actinide | actinide |
| Standard Atomic Weight | 227 u | 257 u |
| Period | 7 | 7 |
| Group | N/A | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Rn]7s26d1 | [Rn] 5f12 7s2 |
| Oxidation states | [3] | [2, 3] |
| Electronegativity (Pauling) | 1.1 | 1.3 |
| Electron affinity | 0.35 eV | 0.339 eV |
| Density | 1.007000e+4 kg/m³ | 9700 kg/m³ |
| Melting point | 1050.85 °C | 1526.85 °C |
| Boiling point | 3197.85 °C | -273.15 °C |
| Discovery year | 1899 | 1952 |