Thorium is a chemical element with symbol Th and atomic number 90. A radioactive actinide metal, thorium is one of only two significantly radioactive elements that still occur naturally in large quantities as a primordial element (the other being uranium). It was discovered in 1828 by the Norwegian Reverend and amateur mineralogist Morten Thrane Esmark and identified by the Swedish chemist Jöns Jakob Berzelius, who named it after Thor, the Norse god of thunder.
90 Atomic Number
232.04 u Atomic Mass
2028.15 K Melting Point
5061 K Boiling Point
11.72 g/cm³ Density
null Å Atomic Radius
2.06 Å Covalent Radius
1.3 Electronegativity
6.31 eV First Ionization Energy
112.72 Electron Affinity
7 Number of Shells
2, 8, 18, 32, 18, 10, 2 Electron Shell Occupations
