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neptunium
[ nep-too-nee-uhm, -tyoo- ]
noun
, Chemistry, Physics.
- a transuranic element produced in nuclear reactors by the neutron bombardment of U-238: decays rapidly to plutonium and then to U-235. : Np; : 93.
neptunium
/ nɛpˈtjuːnɪəm /
noun
- a silvery metallic transuranic element synthesized in the production of plutonium and occurring in trace amounts in uranium ores. Symbol: Np; atomic no: 93; half-life of most stable isotope, 237Np: 2.14 × 10 6years; valency: 3, 4, 5, or 6; relative density: 20.25; melting pt: 639±1°C; boiling pt: 3902°C (est)
neptunium
/ nĕp-to̅o̅′nē-əm /
- A silvery, radioactive metallic element of the actinide series. It occurs naturally in minute amounts in uranium ores and is produced artificially as a byproduct of plutonium production. Its longest-lived isotope is Np 237 with a half-life of 2.1 million years. Atomic number 93.
- See Periodic Table
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Word History and Origins
Origin of neptunium1
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Word History and Origins
Origin of neptunium1
C20: from Neptune ², the planet beyond Uranus, because neptunium is the element beyond uranium in the periodic table
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