Hydrogen vs Promethium
| Property | H Hydrogen | Pm Promethium |
|---|---|---|
| Atomic number | 1 | 61 |
| Symbol | H | Pm |
| Name | Hydrogen | Promethium |
| Category | nonmetal | lanthanide |
| Standard Atomic Weight | 1.007975 u | 145 u |
| Period | 1 | 6 |
| Group | 1 | N/A |
| Block | s | s |
| Phase at STP | gas | solid |
| Electron configuration | 1s1 | [Xe]6s24f5 |
| Oxidation states | [-1, 1] | [2, 3] |
| Electronegativity (Pauling) | 2.2 | N/A |
| Electron affinity | 0.75419 eV | 0.129 eV |
| Density | 0.08988 kg/m³ | 7260 kg/m³ |
| Melting point | -259.34 °C | 1041.85 °C |
| Boiling point | -252.87 °C | 2999.85 °C |
| Discovery year | 1766 | 1902 |