The most common naturally occurring radioactive metal, thorium, is used inside vacuum tubes to allow an electric current to flow. It can also undergo nuclear fission, a process in which atoms split in two and release energy. Ways to make thorium-fueled nuclear reactors that produce electricity are being explored.

Summary of properties (Th)

Atomic weight232.0377(4)
Discoverer (year)Berzelius, Jöns Jacob (1829)
Natural formmetallic solid (face centered cubic)
Electron configuration[Rn] 6d2 7s2
Melting point (ºC)1750
Boiling point (ºC)4790
Abundance in earth's crust (ppm)9.6
Isotope (abundance)232Th (100)
Density g/cm315.4
Van der Waals radius (pm)245
Covalent radius (pm)190
Electronegativity (Pauling)1.3
Vaporization enthalpy (kJ/mol)543.90
Enthalpy of fusion (kJ/mol)13.81
Specific heat capacity (J/g·K) at 25ºC and 1 atm0.11
Thermal conductivity (W/cm·K) at 25ºC and 1 atm0.540
Oxidation state+4
Electron affinity (eV)
1st Ionization potential (eV)6.3067

Back to the Periodic Table of the Elements.