| Pm | Promethium | Rare Earth |
| Atomic number: | 61 | Atomic weight: | (144.9127) | ||
| Shells: | 2,8,18,23,8,2 | Orbitals: | [Xe] 4f5 6s2 | ||
| Melting point: | 1042°C | Boiling point: | 3000°C (estimated) | ||
| Covalent radius: | 1.63 | Å | Atomic volume: | 22.39 | cm³/mol |
| Atomic radius: | 2.62 | Å | Ionic radius: | 1.09 (+3) | Å |
| Electronegativity: | 1.13 | Oxidation states: | |||
| 1st ionization pot.: | 5.55 | V | 2nd ionization pot.: | 10.903 | V |
| 3rd ionization pot.: | 22.283 | V | Specific heat: | 0.18 | J/gK |
| Heat of fusion: | -- | kJ/mol | Heat of vapor.: | -- | kJ/mol |
| Thermal conduct.: | 0.179 | W/cmK | Electrical conduct.: | -- | 10^6/cm ohm |
| Density: | 6.475 | g/cm³ | Valence: | 3 |