Neptunium vs Americium
| Property | Np Neptunium | Am Americium |
|---|---|---|
| Atomic number | 93 | 95 |
| Symbol | Np | Am |
| Name | Neptunium | Americium |
| Category | actinide | actinide |
| Standard Atomic Weight | 237 u | 243 u |
| Period | 7 | 7 |
| Group | N/A | N/A |
| Block | s | s |
| Phase at STP | solid | solid |
| Electron configuration | [Rn]7s25f46d1 | [Rn]7s25f7 |
| Oxidation states | [2, 3, 4, 5, 6, 7] | [2, 3, 4, 5, 6, 7] |
| Electronegativity (Pauling) | 1.36 | 1.3 |
| Electron affinity | 0.48 eV | 0.1 eV |
| Density | 2.025000e+4 kg/m³ | 1.369000e+4 kg/m³ |
| Melting point | 643.85 °C | 1175.85 °C |
| Boiling point | 3901.85 °C | 2010.85 °C |
| Discovery year | 1940 | 1944 |