Rhodium is a rare, silver-white, metallic element that serves mainly as a catalyst, a substance which increases the speed of a chemical reaction. Rhodium is a catalyst in the production of nitric acid and various organic compounds and medicinal drugs. It is also used in catalytic converters, which reduce pollutants in automobile exhausts. Rhodium alloys (metal mixtures) are used in aircraft turbine engines, electric connections, and reflective surfaces of mirrors and searchlights.
Rhodium has the chemical symbol Rh. Its atomic number (number of protons in its nucleus) is 45. Its relative atomic mass is 102.90550. An element’s relative atomic mass equals its mass (amount of matter) divided by 1/12 of the mass of carbon 12, the most abundant form of carbon. Rhodium melts at 1963 °C plus or minus 3 °C and boils at 3697 °C plus or minus 100 °C. Chemists classify rhodium as a transition metal . For information on the position of rhodium on the periodic table, see the article Periodic table .
William H. Wollaston, an English chemist, first isolated rhodium in 1803. Rhodium occurs in Brazil, Canada, Colombia, Russia, South Africa, and Sri Lanka.
