Crossword clues for neptunium
The Collaborative International Dictionary
Neptunium \Nep*tu"ni*um\, n. [NL.] A radioactive metallic element of atomic number 93, produced in nuclear reactors from Plutonium or Uranium. Symbol Np; The atomic weight of the most stable isotope is 237.0482.
Douglas Harper's Etymology Dictionary
1941, from Neptune + element ending -ium. Named for its relative position in the periodic table, next after Uranium, as the planet Neptune is one beyond Uranus. See also plutonium.
Wiktionary
n. The transuranic chemical element with atomic number 93 and symbol Np.
WordNet
n. a radioactive transuranic metallic element; found in trace amounts in uranium ores; a by-product of the production of plutonium [syn: Np, atomic number 93]
Wikipedia
Neptunium is a chemical element with 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 can accumulate 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. 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 widely used as a precursor for the formation of plutonium-238, used in radioisotope thermal generators to provide electricity for spacecraft. Neptunium has also been used in detectors of high-energy neutrons.
The most stable isotope of neptunium, neptunium-237, is a by-product of nuclear reactors and plutonium production. It, and the isotope neptunium-239, are also found in trace amounts in uranium ores due to neutron capture reactions and beta decay. __TOC__
Usage examples of "neptunium".
Nitrogen, Nb for Nobelium, Nd for Neodymium, Ne for Neon, Ni for Nickel, No for Niobrium, Np for Neptunium.
Caius Gracchus, was one sent to this part of Bruttii, under the name of Colonia Minervia Scolacium, a name parallel to those of Colonia Neptunia Tarentum and Colonia Junonia Karthago, decided on at the same time.
And Ireta, a satellite of a suspected third generation sun, ought to be rich in the heavier elements, rich in the transuranics and actinides, neptunium, plutonium and the more esoteric of the rare elements above uranium on the periodic table, so urgently and constantly required by the Federation of Sentient Populations, the search for which was one of the primary tasks of the EEC.
The intermediate elements referred to in this radioactive decay chain are lead (symbol Pb, element 82), polonium (Po, element 84), astatine (At, element 85), francium (Fr, element 87), radium (Ra, element 88), actinium (Ac, element 89), thorium (Th, element 90), protoactinium (Pa, element 91), uranium (U, element 92), neptunium (Np, element 93), and americium (Am, element 95).