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Neptunium
Chemical Properties & Compounds
| Symbol | Atomic Number | Atomic Weight | Melting Point | Boiling Point | Phase | Density | Classification |
| Np | 93 | 237 | 637 °C | 4000 °C | Solid | 20.2 g/cm3 | Metal   |
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| General |
| Name, Symbol, Number |
neptunium, Np, 93 |
| Chemical series |
actinides |
| Group, Period, Block |
n/a, 7, f |
| Appearance |
silvery metallic |
| Standard atomic weight |
(237) g·mol−1 |
| Electron configuration |
[Rn] 5f4 6d1 7s2 |
| Electrons per shell |
2, 8, 18, 32, 22, 9, 2 |
| Physical properties |
| Phase |
solid |
| Density (near r.t.) |
20.2 g·cm−3 |
| Melting point |
910 K
(637 °C, 1179 °F) |
| Boiling point |
4273 K
(4000 °C, 7232 °F) |
| Heat of fusion |
3.20 kJ·mol−1 |
| Heat of vaporization |
336 kJ·mol−1 |
| Heat capacity |
(25 °C) 29.46 J·mol−1·K−1 |
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| Atomic properties |
| Crystal structure |
3 forms: orthorhombic,
tetragonal and cubic |
| Oxidation states |
6, 5, 4, 3
(amphoteric oxide) |
| Electronegativity |
1.36 (scale Pauling) |
| Ionization energies |
1st: 604.5 kJ/mol |
| Atomic radius |
175 pm |
| Miscellaneous |
| Magnetic ordering |
? |
| Electrical resistivity |
(22 °C) 1.220 µΩ·m |
| Thermal conductivity |
(300 K) 6.3 W·m−1·K−1 |
| CAS registry number |
7439-99-8 |
| Selected isotopes |
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| References |
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Neptunium Compounds
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Source: Wikipedia article Neptunium
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Chemistry Quick Facts