Thorium-228

3 definitions found

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

  Thorium \Tho"ri*um\, n. [NL. See {Thorite}.] (Chem.)
     A metallic element found in certain rare minerals, as
     thorite, pyrochlore, monazite, etc., and isolated as an
     infusible gray metallic powder which burns in the air and
     forms thoria; -- formerly called also {thorinum}. Symbol Th.
     Atomic weight 232.0.


     [1913 Webster]

From WordNet (r) 2.0 [wn]:

  thorium
       n : a soft silvery-white tetravalent radioactive metallic
           element; isotope 232 is used as a power source in nuclear
           reactors; occurs in thorite and in monazite sands [syn: {Th},
            {atomic number 90}]

From Elements database 20001107 [elements]:

  thorium
  Symbol: Th
  Atomic number: 90
  Atomic weight: 232.038
  Grey radioactive metallic element. Belongs to actinoids. Found in monazite sand
  in Brazil, India and the US.  Thorium-232 has a half-life of 1.39x10^10 years.
  Can be used as a nuclear fuel for breeder reactors. Thorium-232 captures slow
  {neutron}s and breeds uranium-233. Discovered by Jons J. Berzelius in
  1829.