 Discovery Information
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| Who: E.M. McMillan, P.H. Abelson |
| When: 1940 |
| Where: United States |
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| Name Origin
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| From planet Neptune. |
| "Neptunium" in different languages. |
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| Sources
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| Produced by bombarding uranium with slow neutrons. Neptunium is also found in trace amounts in uranium ores.
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| Its most stable isotope, 237Np, is a by-product of nuclear reactors and plutonium production and it can be used as a component in neutron detection equipment.
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| Uses
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| Used in neutron detection instruments. |
| 237Np is irradiated with neutrons to create 238Pu, a rare and valuable isotope for spacecraft and military applications.
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| History
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| Neptunium (named for the planet Neptune, the next planet out from Uranus, after which uranium was named) was first discovered
by Edwin McMillan and Philip H. Abelson in 1940. Initially predicted by Walter Russell's "spiral" organization of the periodic table, it was found at the Berkeley
Radiation Laboratory of the University of California, Berkeley where the team produced the neptunium isotope 239Np (2.4 day half-life) by bombarding uranium with slow moving neutrons. It was the first transuranium element produced synthetically and the first actinoids series transuranium element discovered.
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| Notes
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| It was the first transuranium element produced synthetically and the first actinoid series transuranium element discovered.
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| 19 neptunium radioisotopes have been characterized, with the most stable being 237Np with a half-life of 2.14 million years, 236Np with a half-life of 154,000 years, and 235Np with a half-life of 396.1 days. All of the remaining radioactive isotopes have half-lives that are less than 4.5 days, and the majority of these have half-lives that are less than 50 minutes.
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