neptunium

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nep·tu·ni·um

 (nĕp-to͞o′nē-əm, -tyo͞o′-)
n. Symbol Np
A silvery, metallic, naturally radioactive element, atomic number 93, the first of the transuranium elements. Its longest-lived isotope is Np-237 with a half-life of 2.1 million years. Found in trace quantities in uranium ores, it is produced synthetically by nuclear reactions. See Periodic Table.

[After the planet Neptune (from the fact that it follows uranium in the periodic table).]

neptunium

(nɛpˈtjuːnɪəm)
n
(Elements & Compounds) 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 × 106 years; valency: 3, 4, 5, or 6; relative density: 20.25; melting pt: 639±1°C; boiling pt: 3902°C (est)
[C20: from Neptune2, the planet beyond Uranus, because neptunium is the element beyond uranium in the periodic table]

nep•tu•ni•um

(nɛpˈtu ni əm, -ˈtyu-)

n.
a short-lived radioactive transuranic element produced in nuclear reactors by the neutron bombardment of U-238. Symbol: Np; at. no.: 93; at. wt.: 237.
[1940–45; Neptune + -ium2]

nep·tu·ni·um

(nĕp-to͞o′nē-əm)
Symbol Np A silvery, radioactive metallic element of the actinide series. It occurs naturally in minute amounts in uranium ores and is produced artificially as a by-product of plutonium production. The most stable isotope of neptunium has a half-life of 2.1 million years. Atomic number 93. See Periodic Table.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.neptunium - a radioactive transuranic metallic elementneptunium - a radioactive transuranic metallic element; found in trace amounts in uranium ores; a by-product of the production of plutonium
metal, metallic element - any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.
Translations
нептуний
neptunium
neptunium
neptunio
neptuunium
neptunium
neptunium
neptunij
neptúnium
nettunio
ネプツニウム
neptunium
neptunium
neptun
neptuniu
neptunium
neptunij
neptunium
neptünyum

neptunium

[nepˈtjuːnɪəm] Nneptunio m

neptunium

n (Chem) → Neptunium nt
References in periodicals archive ?
For example the half life - a measure of the rate of natural decay of radioactive materials - of the waste product Plutonium 239 is 24,000 years, and that of Neptunium 237 is two million years.
For example the half life -- a measure of the rate of natural decay of radioactive materials -- of the waste product Plutonium 239 is 24,000 years, and that of Neptunium 237 is two million years.
2 percent of current stocks are highly radioactive, but some of the material, such as neptunium 237, can remain radioactive for more than two million years, the report noted.