neptuniumn.
/nɛpˈtjuːnɪəm/, /nɛpˈtʃuːnɪəm/, U.S. /nɛpˈt(j)uniəm/ Chemistry.
1. R. Hermann's name for: a supposed metallic element discovered in the mineral tantalite. disused.
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neptunium1877
1877 Jrnl. Chem. Soc. 32 167 Neptunium is distinguished from tantalum by the fact that its fluoride forms an easily soluble double salt with potassium fluoride.
1916 Science 21 July 102/2 Neptunium..is described as belonging to the ‘tantalum group’, of the atomic weight 118, and as occurring in certain rare earths associated with tantalum and niobium.
2. A radioactive chemical element of the actinide series, atomic no. 93, which is a silvery metal and was first produced artificially as a product of the bombardment of uranium with neutrons, although traces of it occur naturally in uranium ores. Symbol Np.The word does not occur in the article by E. M. McMillan and P. H. Abelson ( Physical Rev. (1940) 57 1185) in which they announced the discovery of the element, though McMillan is generally said to be the coiner (e.g. quot. 1942).
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neptunium1941
1941 Sci. News Let. 30 Aug. 135/1 The uranium outpost was passed some years ago by Prof. Enrico Fermi..with his discovery of the radioactive element No. 93, now called neptunium.
1942 G. T. Seaborg & A. C. Wahl Chem. Properties Elem. 94 & 93 (U.S. Office Sci. Res. & Devel. Report A–135) 17 Following McMillan, who has suggested the name neptunium..for element 93, we are using plutonium..for element 94... The corresponding chemical symbols would be Np and Pu.
1950 M. Lowry Let. 6 Mar. (1967) 200 Oddly enough I put neptunium in but abandoned it for niobium... I just took the elements out of the dictionary.
1968 New Scientist 23 May 410/2 Neptunium-237 is an important isotope because it is the precursor of plutonium-238.
1990 C. Rose Dirty Man of Europe (1991) 3 Some of the plutonium now found along the Cumbrian coast and in the Irish Sea, will end up as neptunium.
This entry has been updated (OED Third Edition, September 2003; most recently modified version published online March 2022).
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n.1877