Chemistry - Thorium
Thorium is one of the radioactive actinide metals that occur naturally in large quantities.
The symbol of thorium is ‘Th’ and atomic number is ’90.’
In 1829, a Norwegian mineralogist Morten Thrane Esmark, first discovered thorium.
Jöns Jacob Berzelius, the Swedish chemist, identified and named it ‘thorium’ after the name of ‘Thor’, the Norse god of thunder.
Salient Features of Thorium
Thorium is paramagnetic and soft radioactive actinide metal.
Thorium metal’s color is silvery; when it exposed to air, it tarnishes black and form dioxide.
All isotopes of thorium are unstable and it is a weak radioactive element.
Among all the significant radioactive elements, the half-life of thorium is the longest, i.e. about 14.05 billion years.
The melting point of thorium is about 17500C.
Occurrence of Thorium
Thorium is primordial element that exists existed in its current form since before the Earth was formed.
Thorium, found in the earth’s crust, is refined from the monazite sands.
Monazite that occurs in large amounts across the world is the most important source of thorium.
Alloys of Thorium
Mag-Thor and thorium-aluminum are the most significant alloys of thorium, Magnesium, and aluminum.
Compounds of Thorium
Following are the major compounds of Thorium −
Thorium dioxide - ThO2
Thorium (IV) sulfide - ThS2
Thorium (IV) iodide - ThI4
Thorium tetrafluoride - ThF4
Thorium (IV chloride - ThCl4
Thorium (IV) carbide - ThC
Some others are −
Thorium (IV) nitrate
Thorium (IV) orthosilicate
Uses of Thorium
Thorium is normally used in gas tungsten arc welding (GTAW) because it (thorium) increases the high-temperature strength of tungsten electrodes and accordingly improve arc stability.
In electronic equipment, the application of thorium coating on tungsten wire, increases the electron emission of heated cathodes.
In chemical industry, the dioxide of thorium namely ‘thoria’ is commonly used.