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| Neptunium | Neptunium | Neptunij | Nettunio | Neptunium | ||||||||||||||||||||
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Np Neptunium |
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- Neptunium was discovered by Edwin M. McMillan and P. H. Abelson (USA) in 1940. Named after the planet Neptune. It is rare, silvery radioactive metal. Resists alkalis; reacts with oxygen and acids. Attacked by steam. Radiotoxic.
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TRANSITION ELEMENT: ACTINIDE | |
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| Relative atomic mass: | [237] | Electronic configuration: | [Rn] 5f4 6d1 7s2 |
| Formal oxidation number: | +3 +4 +5 +6 | Electronegativities: | 1.3 |
| Thermal conductivity: | 6.3 W m-1 K-1 | Electrical resistivity (20 °C): | 122 μΩcm |
| Atomic radius: | 130 pm | Standard state (20 °C): | solid |
| Density (g dm-3): | 20250 (293 K) | Molar volume (cm3 mol-1): | 11.70 (293 K) |
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THERMAL PROPERTIES | |
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| Melting point: | 644 °C | Heat of fusion: | 9.46 kJ mol-1 |
| Boiling point: | 3902 °C | Heat of vaporization: | 336.6 kJ mol-1 |
| Critical temperature: | 11727 °C | Heat of atomization: | 457 kJ mol-1 |
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IONIZATION ENERGIES AND ABUNDANCE | |
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| 1st ionization energy: | 604.55 kJ mol-1 | Abundance of element (air): | - ppm |
| 2nd ionization energy: | - kJ mol-1 | Abundance of element (Earth's crust): | - ppm |
| 3rd ionization energy: | - kJ mol-1 | Abundance of element (oceans): | - ppm |
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ISOTOPES | |
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Isotopes | Relative atomic mass | Abundance (%) |
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237Np | 237.048167(2) | * |
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MINERALS AND USES | |
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- Neptunium was produced by bombarding uranium with slow neutrons.
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REDUCTION POTENTIALS | |
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Balanced half-reaction | Eo / V | Annotation |
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