IYPT 2019 Elements 045: Rhodium: Catalytic converters and jewellery

Element 45 in our International Year of the Periodic Table series is rhodium. This rare, unreactive element finds uses in the catalytic converters in our cars and in electroplated white gold jewellery.

Rhodium is one of a number of transition metals used in the catalytic converters found in diesel and petrol cars. These converters help break down polluting compounds in car engine exhaust fumes into less harmful compounds. Other metals used in catalytic converters include palladium and platinum. There’s more on how they work in this graphic.

Another use of rhodium is in the electroplating of white gold jewellery. This adds hardness and a silvery shine. Rhodium is one of the least reactive elements in the periodic table, so it does not tarnish or damage easily over time.

Rhodium is one of the rarest elements in the Earth’s crust – rarer than gold or platinum, and costlier than both per gram.

Remember, you can keep track of all of the previous entries in this series on the site here, or on the Royal Society of Chemistry’s dedicated page.