Thorium was discovered in 1828 in the mineral thorite by Jons Berzelius. Its name comes after Thor (Scandinavian god of war). It is mildly radioactive and has 10 isotopes. Naturally occurring 232Th goes 10 decay steps before reaching stable lead 208Pb, and also emits thoron gas 220Rn.
|isotope||mass||isotopic abundance (%)|
|232Th||232.0380495||100 = (Natural radioactivity isotope)|
|isotope||half life||disintegration form|
|230Th||7.538 x 104 years||alpha|
|232Th||1.405 x 1010 years||alpha|