The Element Rhodium
Atomic Number: 45
Atomic Weight: 102.90550
Melting Point: 2237 K (1964°C or 3567°F)
Boiling Point: 3968 K (3695°C or 6683°F)
Density: 12.4 grams per cubic centimeter
Phase at Room Temperature: Solid
Element Classification: Metal
Period Number: 5
Group Number: 9
Group Name: none
What's in a name? From the Greek word for rose, rhodon.
Say what? Rhodium is pronounced as RO-dee-em.
History and Uses:
Rhodium was discovered by William Hyde Wollaston, an English chemist, in 1803 shortly after his discovery of the element palladium. He obtained rhodium from a sample of platinum ore that was obtained from South America. After removing the platinum and palladium from the sample, he was left with a dark red powder. The powder turned out to be sodium rhodium chloride (Na3RhCl6·12H2O). Wollaston obtained rhodium from the powder by treating it with hydrogen gas (H2). Rhodium tends to occur along with deposits of platinum and is primarily obtained as a byproduct of mining and refining platinum. Rhodium is also obtained as a byproduct of the nickel mining operation in the Sudbury region of Ontario, Canada.
Rhodium is used to make electrical contacts, as jewelry and in catalytic converters, but is most frequently used as an alloying agent in other materials, such as platinum and palladium. These alloys are used to make such things as furnace coils, electrodes for aircraft spark plugs and laboratory crucibles.
Estimated Crustal Abundance: 1×10-3 milligrams per kilogram
Estimated Oceanic Abundance: Not Applicable
Number of Stable Isotopes: 1 (View all isotope data)
Ionization Energy: 7.459 eV
Oxidation States: +3
3s2 3p6 3d10
4s2 4p6 4d8