All practice pages/Interatomic theory/Elements
Element 90, an actinide
Named after the Norse god of thunder, far more abundant than uranium, and a possible fuel for future nuclear reactors.
Period 7, in the actinide row set below the main table. The other actinides are tinted, and every cell opens its own article.
Radioactive, like every actinide. It gives up electrons to form positive ions.
About three times as abundant in the crust as uranium, found mostly in monazite sands in India, Brazil and elsewhere.
Jöns Jacob Berzelius identified it in 1829 in a black mineral from Norway sent to him by Morten Thrane Esmark, and named it after Thor. In 1898 Marie Curie and Gerhard Carl Schmidt each found that it was radioactive.
Thorium oxide once made gas lantern mantles glow brightly and still goes into heat-resistant ceramics, and thoriated tungsten makes welding electrodes. In a reactor thorium can be turned into uranium-233 fuel, and thorium reactors are being developed in India and China.
Weakly radioactive, and its dust is dangerous to inhale. Old camping lantern mantles and some vintage camera lenses contain thorium.