Thorium is the second member of the actinides located on the second row below the periodic table. It is a silvery, radioactive metal with a melting point of 1750 degrees Celsius. It was discovered in 1828 by Jons Jacob Berzelius. It is a reactive metal that quickly forms oxides on exposure to air. It has a half life of 14 billion years. 

Thorium oxide used to be used in gas powered lanterns, but it is now outdated due to its radioactivity and toxicity. Thorium may play a role in the future as being a fuel for nuclear reactors as it would be safer and cheaper than uranium.