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Neptunium - Np General Information Discovery Neptunium was discovered by E.M. McMillan and P. Abelson in 1940 in California, USA. Appearance Neptunium is a radioactive silvery metal. Source Neptunium is obtained as a by-product from nuclear reactors. Trace quantities occur naturally in uranium ores. Uses Neptunium is little used outside research. Biological Role Neptunium has no known biological role. It is toxic due to its radioactivity. General Information Neptunium is attacked by oxygen, steam and acids, but not by alkalis. |
| Physical Information | |||
| Atomic Number | 93 | ||
| Relative Atomic Mass (12C=12.000) | 237.05 | ||
| Melting Point/K | 913 | ||
| Boiling Point/K | 4175 | ||
| Density/kg m-3 | 20250 (293K) | ||
| Ground State Electron Configuration | [Rn]5f46d17s2 |
| Key Isotopes | ||||||
| nuclide | 237Np | |||||
| atomic mass | 237.05 | |||||
| natural abundance | 0% | |||||
| half-life | 2.14x106 yrs |
| Other Information | ||
| Enthalpy of Fusion/kJ mol-1 | 9.46 | |
| Enthalpy of Vaporisation/kJ mol-1 | 336.6 | |
| Oxidation States | ||
| main | NpV | |
| others | NpII, NpIII, NpIV, NpVI, NpVII | |
| Covalent Bonds /kJ mol-1 | ||
| not applicable | ||
| Ionisation Energies/kJ mol-1 | ||
| M - M+ | 597 | |
| M+ - M2+ | ||
| M2+ - M3+ | ||
| M3+ - M4+ | ||
| M4+ - M5+ | ||
| M5+ - M6+ | ||
| M6+ - M7+ | ||
| M7+ - M8+ | ||
| M8+ - M9+ | ||
| M9+ - M10+ | ||
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