Promethium

2 definitions found

From WordNet (r) 2.0 [wn]:

  promethium
       n : a soft silvery metallic element of the rare earth group
           having no stable isotope; was discovered in radioactive
           form as a fission product of uranium [syn: {Pm}, {atomic
           number 61}]



From Elements database 20001107 [elements]:

  promethium
  Symbol: Pm
  Atomic number: 61
  Atomic weight: (147)
  Soft silvery metallic element, belongs to the lanthanoids. Pm-147, the
  only natural isotope, is radioactive and has a half-life of 252 years.
  Eighteen radioisotopes have been produced, but all have very short
  half-lives. Found only in nuclear decay waste. Pm-147 is of interest as a
  beta-decay source, however Pm-146 and Pm-148 have to be removed from it
  first, as they generate gamma radiation. Discovered by J.A. Marinsky,
  L.E. Glendenin and C.D. Coryell in 1947.