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).]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

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]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.

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.
The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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.
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
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
Collins Spanish Dictionary - Complete and Unabridged 8th Edition 2005 © William Collins Sons & Co. Ltd. 1971, 1988 © HarperCollins Publishers 1992, 1993, 1996, 1997, 2000, 2003, 2005

neptunium

n (Chem) → Neptunium nt
Collins German Dictionary – Complete and Unabridged 7th Edition 2005. © William Collins Sons & Co. Ltd. 1980 © HarperCollins Publishers 1991, 1997, 1999, 2004, 2005, 2007
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.
Only 0.2 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.