Symbol Th
Atomic Number 90
Atomic Mass 232.038 g.mol 1
Discovered by Jöns Jacob Berzelius in 1829

Chemical Properties of Thorium

Group 12 Melting point 1750°C, 3182°F, 2023 K
Period 7 Boiling point 4785°C, 8645°F, 5058 K
Block f Density (g cm3) 11.7
Atomic number 90 Relative atomic mass 232.038  
State at 20°C Solid Key isotopes 230Th, 232Th
Electron configuration [Rn] 6d27s2 CAS number 7440-29-1
ChemSpider ID 22399 ChemSpider is a free chemical structure database

What is Thorium?

  • Thorium is a chemical element with atomic number 90 and represented with the symbol ‘Th’ in the periodic table.
  • In its pure form, it is a silvery white metal which is stable in air and remains lustrous for several months. When it reacts with oxides it slowly transforms into a gray color.
  • Thorium is a weak radioactive metal as its isotopes are highly unstable. It is estimated that the element This is more abundant than Uranium in the Earth’s crust. It is found in small amounts in most rocks and soils.
  • Thorium is named after Thor, The Scandinavian God of war. It was discovered by a Swedish Scientist named Jons Jacob Berzelius in the year 1828.

Physical properties of Thorium

  • The properties of thorium depend highly on a number of impurities present in the sample. The major impurity is commonly thorium dioxide. The element is an electropositive metal and is highly reactive. It burns magnificently with a white light when heated in the air.It has 90 electrons and has 4 electrons in the valence shell.
  • At constant pressure and temperature, Thorium is slowly attacked by water but does not readily dissolve in acids.

Applications of Thorium

  • As thorium is radioactive, its uses mainly lie in nuclear fuel applications.
  • It is helpful in radiometric dating.
  • Used as an alloying element in magnesium, to coat tungsten wire in electrical equipment.
  • Used in manufacturing of lenses for cameras and scientific instruments.
  • Used in nuclear reactors as it does not generate plutonium.

Health effects of Thorium

  • As it is found almost everywhere on the earth, people will always be exposed to small amounts of thorium through the air, food, and water. But inhaling or taking small amounts of the element will not have harmful effects but continuous exposure to it may cause lung cancer. Sometimes it may even cause pancreas diseases.

Practise This Question

Fluorine forms more than one oxoacid - True or False?