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Author: langbot
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English[en]
Neptunium is a chemical element with the symbol Np and atomic number 93. A radioactive actinide metal, neptunium is the first transuranic element. Its position in the periodic table just after uranium, named after the planet Uranus, led to it being named after Neptune, the next planet beyond Uranus. A neptunium atom has 93 protons and 93 electrons, of which seven are valence electrons. Neptunium metal is silvery and tarnishes when exposed to air. The element occurs in three allotropic forms and it normally exhibits five oxidation states, ranging from +3 to +7. It is radioactive, poisonous, pyrophoric, and capable of accumulating in bones, which makes the handling of neptunium dangerous. Although many false claims of its discovery were made over the years, the element was first synthesized by Edwin McMillan and Philip H. Abelson at the Berkeley Radiation Laboratory in 1940.[4] Since then, most neptunium has been and still is produced by neutron irradiation of uranium in nuclear reactors. The vast majority is generated as a by-product in conventional nuclear power reactors. While neptunium itself has no commercial uses at present, it is used as a precursor for the formation of plutonium-238, and in radioisotope thermal generators to provide electricity for spacecraft. Neptunium has also been used in detectors of high-energy neutrons.
Cornish[kw]
Elven gymyk yw neptuniom, niver 93 y'n Vosen Beriodek. Y furvell gymyk yw Np. An hanow a dheu dhyworth an planet Nevyon, drefen bos uraniom henwys dhyworth Ouranos. Nyns eus dhe neptuniom rann y'n korf denel. Ny hwer neptuniom war an nor marnas yn arbrovjiow hwithrans. Diskudhans veu neptuniom yn mis Me 1940 gans Edwin McMillan (1907-1991) ha Philip Abelson (1913-2004) yn Berkeley, Kaliforni. McMillan a gevrannas an Pewas Nobel rag Kymyk yn 1951 gans Glenn Seaborg drefen aga thiskudhyansow. Askorrys yw neptuniom dhyworth keunys uraniom usys yn dasoberoryon nuklerek. Nebes radyoeythresek yw. Usys yw yn sensellow nywtron. Poos atomek neptuniom yw 237, y boynt teudhi yw 640°C ha'y boynt bryjyon yw 3902°C. Y dhosedh yw 20.3kg an liter. Alkan arghansek yw neptuniom. Radyoweythresek yw pub isotop neptuniom, an isotop gans an hanter-bewnans hirra yw neptuniom-237, 2.14 milvil a vledhynnyow.