Cerium vs Promethium
| Property | Ce Cerium | Pm Promethium |
|---|---|---|
| Atomic number | 58 | 61 |
| Symbol | Ce | Pm |
| Name | Cerium | Promethium |
| Category | lanthanide | lanthanide |
| Standard Atomic Weight | 140.116 u | 145 u |
| Period | 6 | 6 |
| Group | N/A | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Xe]6s24f15d1 | [Xe]6s24f5 |
| Oxidation states | [1, 2, 3, 4] | [2, 3] |
| Electronegativity (Pauling) | 1.12 | N/A |
| Electron affinity | 0.955 eV | 0.129 eV |
| Density | 6770 kg/m³ | 7260 kg/m³ |
| Melting point | 797.85 °C | 1041.85 °C |
| Boiling point | 3423.85 °C | 2999.85 °C |
| Discovery year | 1801 | 1902 |