Actinium vs Thorium
Pick up to 3 elements and see how they stack up.
| Property | Actinium | Thorium |
|---|---|---|
| Atomic number | 89 | 90 |
| Atomic mass | 227 | 232.04 |
| Electronegativity | 1.1 | 1.3 |
| Melting point | 1,323 K (1,049.8 °C) | 2,023 K (1,749.8 °C) |
| Boiling point | 3,471 K (3,197.8 °C) | 5,061 K (4,787.8 °C) |
| Density | 10.07 g/cm³ | 11.72 g/cm³ |
| Atomic radius | 260 pm | 237 pm |
| Ionization energy | 5.17 eV | 6.08 eV |
| Discovered | 1899 | 1829 |
| Category | Actinide | Actinide |
| State at room temp. | Solid | Solid |
| Block | f | f |
| Group | — | — |
| Period | 7 | 7 |
| Valence electrons | 2 | 2 |
| Common charges | +3 | +4 |
| Electron configuration | [Rn] 6d1 7s2 | [Rn] 6d2 7s2 |