thorium

[thawr-ee-uh m, thohr-] /ˈθɔr i əm, ˈθoʊr-/
noun, Chemistry
1.
a grayish-white, lustrous, somewhat ductile and malleable, radioactive metallic element present in monazite: used as a source of nuclear energy, as a coating on sun-lamp and vacuum-tube filament coatings, and in alloys. Symbol: Th; atomic weight: 232.038; atomic number: 90; specific gravity: 11.7.
Compare thoria.
Origin
< Neo-Latin (1829); see Thor, -ium
Related forms
thoric
[thawr-ik, thor-] /ˈθɔr ɪk, ˈθɒr-/ (Show IPA), adjective
Examples from the web for thorium
  • She soon repeated the experiment with thorium, which behaved in similar ways.
  • Phosphate rock sequesters uranium, thorium, and decay daughters.
  • The reason is that the ash left over when coal is burned contains radioactive elements, notably uranium and thorium.
  • thorium hardly gets a mention as a safer option, there is more thorium around than uranium.
  • Exploiting the thorium cycle, the fuel supply is enormous.
  • They also tend to occur in deposits with radioactive elements, particularly thorium and uranium.
  • Helium is a finite and increasingly scarce resource, produced extremely slowly by decaying uranium and thorium.
  • If fueled with thorium, heavy-water reactors can become full breeders.
  • Some refer to these variously as thorium salt reactors.
  • In the environment, thorium exists in combination with other minerals, such as silica.
British Dictionary definitions for thorium

thorium

/ˈθɔːrɪəm/
noun
1.
a soft ductile silvery-white metallic element. It is radioactive and occurs in thorite and monazite: used in gas mantles, magnesium alloys, electronic equipment, and as a nuclear power source. Symbol: Th; atomic no: 90; atomic wt: 232.0381; half-life of most stable isotope, 232Th: 1.41 × 1010 years; valency: 4; relative density: 11.72; melting pt: 1755°C; boiling pt: 4788°C
Derived Forms
thoric, adjective
Word Origin
C19: New Latin, from Thor + -ium
Word Origin and History for thorium
n.

rare metallic element, 1832, Modern Latin, named 1828-9 by its discoverer, Swedish chemist Jöns Jakob Berzelius (1779-1848) in honor of the Scandinavian god Thor.

thorium in Medicine

thorium tho·ri·um (thôr'ē-əm)
n.
Symbol Th
A radioactive metallic element that is used in magnesium alloys; its longest-lived isotope, Th 232, has a half-life of 1.41 × 1010 years. Atomic number 90; atomic weight 232.038; approximate melting point 1,750°C; approximate boiling point 4,800°C; approximate specific gravity 11.7; valence 4.

thorium in Science
thorium
  (thôr'ē-əm)   
Symbol Th
A silvery-white, radioactive metallic element of the actinide series. It is used for fuel in some nuclear reactors and for improving the high-temperature strength of magnesium alloys. The only naturally occurring isotope of thorium, Th 232, is also its most stable, having a half-life of 14.1 billion years. Atomic number 90; atomic weight 232.038; approximate melting point 1,750°C; approximate boiling point 4,500°C; approximate specific gravity 11.7; valence 4. See Periodic Table.