Iridium is a chemical element with the symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, It is considered to be the second-densest metal (after osmium) with a density of 22.56 g/cm3 as defined by experimental X-ray crystallography.
Chemical Element Properties of Ir
|Melting point||2,410° C|
|Boiling point||4,527° C|
|Discovered by||Ghiorso in 1952|
It was discovered in 1803 among insoluble impurities in natural platinum. Smithson Tennant, the primary discoverer, named iridium after the Greek goddess Iris, the personification of the rainbow, because of the striking and diverse colors of its salts. It is one of the rarest elements in Earth’s crust, with annual production and consumption of only three tonnes.
Physical Properties of Iridium
- It is silverish-white and it is known to be the most corrosion-resistant element known. It is unaffected by air, water, and acids.
- Ir is one of the lesser-known members of the platinum group, Ir possesses quite remarkable physical and chemical properties.
- Not only is it the most corrosion-resistant of all metals, it is insoluble in all mineral acids at high temperatures, but has a very high melting point and is the only metal that can maintain good mechanical properties in air temperatures above 1600°C.
- It has a high modulus of rigidity and elasticity.
Uses of Iridium
- The main use of iridium is as a hardening agent for platinum alloys.
- It is used in making crucibles and other equipment that is used at high temperatures.
- It is also used to make heavy-duty electrical contacts.
- Ir was used in making the international standard kilogram, which is an alloy of 90% platinum and 10% iridium.
- Radioactive isotopes of iridium are used in radiation therapy for the treatment of cancer.
Applications of Iridium
- Nowadays the automotive industry, chemical industry, and electronic industry have the most demand for iridium, where it is used to coat the electrodes in the Chlor-alkali process and catalysts.
- It is also known to be used in Space vehicles and Satellites.