Thorium Selenide

See more Thorium products. Thorium (atomic symbol: Th, atomic number: 90) is a Block F, Group 3, Period 7 element with an atomic weight of 232.03806. The number of electrons in each of thorium's shells is [2, 8, 18, 32, 18, 10, 2] and its electron configuration is [Rn] 6d² 7s². The thorium atom has a radius of 179 pm and a Van der Waals radius of 237 pm. Thorium was first discovered by Jöns Jakob Berzelius in 1829. The name Thorium originates from the Scandinavian god Thor, the Norse god of war and thunder. In its elemental form, thorium has a silvery, sometimes black-tarnished, appearance. It is found in small amounts in most rocks and soils. Thorium is a radioactive element that is currently the best contender for replacing uranium as nuclear fuel for nuclear reactors. It provides greater safety benefits, an absence of non-fertile isotopes, and it is both more available and abundant in the Earth's crust than uranium.