Rhodium Facts - Periodic Table of the Elements

Rhodium Facts - Periodic Table of the Elements Rhodium  Basic Facts Atomic Number: 45 Symbol: Rh Atomic Weight: 102.9055 Discovery: William Wollaston 1803-1804 (England) Electron Configuration: [Kr] 5s1 4d8 Word Origin: Greek rhodon rose. Rhodium salts yield a rosy-colored solution. Properties: Rhodium metal is silvery-white. When exposed to red heat, the metal slowly changes in air to the sesquioxide. At higher temperatures it converts back to its elemental form. Rhodium has a higher melting point and lower density than platinum. The melting point of rhodium is 1966 /-3 °C, boiling point 3727 /-100 °C, specific gravity 12.41 (20 °C), with a valence of 2, 3, 4, 5, and 6. Uses: One major use of rhodium is as an alloying agent to harden platinum and palladium. Because it has a low electrical resistance, rhodium is useful as an electrical contact material. Rhodium has a low and stable contact resistance and is highly resistant to corrosion. Plated rhodium is very hard and has a high reflectance, which makes it useful for optical instruments and jewelry. Rhodium is also used as a catalyst in certain reactions. Sources: Rhodium occurs with other platinum metals in river sands in the Urals and in North and South America. It is found in the copper-nickel sulfide ores of the Sudbury, Ontario region. Element Classification: Transition Metal Rhodium Physical Data Density (g/cc): 12.41 Melting Point (K): 2239 Boiling Point (K): 4000 Appearance: silvery-white, hard metal Atomic Radius (pm): 134 Atomic Volume (cc/mol): 8.3 Covalent Radius (pm): 125 Ionic Radius: 68 (3e) Specific Heat (20 °C J/g mol): 0.244 Fusion Heat (kJ/mol): 21.8 Evaporation Heat (kJ/mol): 494 Pauling Negativity Number: 2.28 First Ionizing Energy (kJ/mol): 719.5 Oxidation States: 5, 4, 3, 2, 1, 0 Lattice Structure: Face-Centered Cubic Lattice Constant (Ã…): 3.800 References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Langes Handbook of Chemistry (1952), CRC Handbook of Chemistry Physics (18th Ed.) Return to the Periodic Table Chemistry Encyclopedia