tho·ri·um /ˈθoriəm, ˈθɔr-/
 放射性金屬元素,符號Th,原子序90,釷


 tho·ri·um /ˈθorɪəm, ˈθɔr-/ 名詞
 釷


 Tho·ri·um n.  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.

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 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]


 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
 neutrons and breeds uranium-233. Discovered by Jons J. Berzelius in
 1829.