| Th | Thorium | Rare Earth |
| Atomic number: | 90 | Atomic weight: | 232.0381 | ||
| Shells: | 2,8,18,32,18,10,2 | Orbitals: | [Rn] 6d2 7s2 | ||
| Melting point: | 1750°C | Boiling point: | 4000°C | ||
| Covalent radius: | 1.65 | Å | Atomic volume: | 19.9 | cm³/mol |
| Atomic radius: | -- | Å | Ionic radius: | 1.05 (+4) | Å |
| Electronegativity: | 1.3 | Oxidation states: | |||
| 1st ionization pot.: | 6.08 | V | 2nd ionization pot.: | 11.504 | V |
| 3rd ionization pot.: | 20.003 | V | Specific heat: | 0.12 | J/gK |
| Heat of fusion: | 16.10 | kJ/mol | Heat of vapor.: | 514.40 | kJ/mol |
| Thermal conduct.: | 0.540 | W/cmK | Electrical conduct.: | 0.0653 | 10^6/cm ohm |
| Density: | 11.7 | g/cm³ | Valence: | 4 |