Rhodium

Rhodium (Rh) is a chemical element and a metal with atomic number 45. It belongs to the platinum group metals, which also include platinum, palladium, iridium, osmium, and ruthenium. Rhodium is a silvery-white metal that is hard and resistant to corrosion and oxidation.

This element is extremely rare in the Earth's crust and ranks among the most expensive metals in commerce. It is obtained primarily as a byproduct during the refining of nickel and platinum ores, rather than as a principal ore itself.

History of discovery

Rhodium was identified in the early nineteenth century by the English scientist William Hyde Wollaston, who isolated it at the same time as palladium. The name derives from the Greek word for "rose" (rhodon), because certain solutions of the element have a rose-red color.

Properties

Rhodium has a high melting point and conducts electricity and heat well. It does not corrode under ordinary conditions, and its resistance to corrosion makes it useful as a plating for other metals to maintain their appearance and luster.

Applications

The primary use of rhodium is in catalysts installed in automotive emission control systems. There it helps convert nitrogen oxides into nitrogen and oxygen. It is also used in electroplating, jewelry coating, laboratory mirrors, and chemical manufacturing.