Thorium is a chemical element with the symbol Th and atomic number 90 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. It 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. It is named after Thor, The Scandinavian God of war. It was discovered by a Swedish Scientist named Jons Jacob Berzelius in the year 1829.
Thorium is still being used as an alloying element in TIG welding electrodes but is slowly being replaced in the field with different compositions. It was also material in high-end optics and scientific instrumentation, and as the light source in gas mantles, but these uses have become marginal. It has been suggested as a replacement for uranium as nuclear fuel in nuclear reactors, and several thorium reactors have been built.
Physical Properties of Thorium
- 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, Th is slowly attacked by water but does not readily dissolve in acids.
- Tetravalent thorium compounds are usually colorless or yellow, like those of silver or lead, as the Th4+ ion has no 5f or 6d electrons.
- Thorium chemistry is therefore largely that of an electropositive metal forming a single diamagnetic ion with a stable noble-gas configuration, indicating a similarity between thorium and the main group elements of the s-block.