Neptunium

3 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  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.
     [PJC]



From WordNet (r) 2.0 [wn]:

  neptunium
       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}]

From Elements database 20001107 [elements]:

  neptunium
  Symbol: Np
  Atomic number: 93
  Atomic weight: (237)
  Radioactive metallic transuranic element, belongs to the actinoids.
  Np-237, the most stable isotope, has a half-life of 2.2*10^6 years and is
  a by product of nuclear reactors. The other known isotopes have mass
  numbers 229 through 236, and 238 through 241. Np-236 has a half-life of
  5*10^3 years. First produced by Edwin M. McMillan and P.H. Abelson in
  1940.