'Thorium' definitions:
Definition of 'thorium'
From: WordNet
noun
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: thorium, Th, atomic number 90]
Definition of 'Thorium'
From: 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]
Definition of 'Thorium'
From: Elements
- 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.