Thorium vs Protactinium
| Property | Th Thorium | Pa Protactinium |
|---|---|---|
| Atomic number | 90 | 91 |
| Symbol | Th | Pa |
| Name | Thorium | Protactinium |
| Category | actinide | actinide |
| Standard Atomic Weight | 232.0377 u | 231.03588 u |
| Period | 7 | 7 |
| Group | N/A | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Rn]7s26d2 | [Rn]7s25f26d1 |
| Oxidation states | [-1, 1, 2, 3, 4] | [2, 3, 4, 5] |
| Electronegativity (Pauling) | 1.3 | 1.5 |
| Electron affinity | 0.607 eV | 0.123 eV |
| Density | 1.172000e+4 kg/m³ | 1.537000e+4 kg/m³ |
| Melting point | 1749.85 °C | 1571.85 °C |
| Boiling point | 4787.85 °C | -273.15 °C |
| Discovery year | 1828 | 1913 |