rh

Rh is the chemical symbol for rhodium, an element with atomic number 45 that belongs to the platinum group of transition metals. It was discovered in 1803 by William Hyde Wollaston as a byproduct of dissolving platinum ore; he named it rhodium from the Greek rhodon, meaning rose, in reference to the pink color of rhodium salts.

Rhodium is a hard, dense, silvery-white metal with a bright, highly reflective surface. It has a high melting point of about 1,964°C and possesses excellent resistance to corrosion and oxidation, properties that contribute to its value in high-performance applications and coatings.

Rhodium is rare in Earth’s crust and is typically found with other platinum-group metals in ultrabasic igneous rocks. Principal sources include the Bushveld Complex in South Africa and the Urals in Russia, where it is refined as a byproduct of platinum and nickel mining.

The most important use of rhodium is as a catalyst in automotive catalytic converters and in other chemical processes. It is also employed to produce hard-wearing platinum-group metal alloys and to plate jewelry and laboratory equipment, providing tarnish resistance and enhanced reflectivity.

Isotopes and occurrence: Natural rhodium occurs as a single stable isotope, 103Rh; many radioactive isotopes exist, produced in reactors or accelerators.

Safety: Rhodium metal is relatively inert and of low chemical toxicity, but fine powders pose inhalation risks; standard industrial hygiene practices apply.

Note: Rh can also refer to the Rhesus factor in blood typing, a biological term unrelated to the element.