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Metal > RhodiumRh - Rhodium This transition element was discovered in 1803 by Wollaston in London. Atomic number - 45 Density g/mL 12 .4 Atomic weight u 102 .9055 Melting point K 2236 Bonding radius A 1 .25 Boiling point K 3970 Atomic radius A 1 .83 Heat of vaporization kJ/mol 493 Ionization Potential V 7 .46 Heat of fusion kJ/mol 21 .5 Electronegativity - 2 .28 Specific heat J/gK 0 .242 The oxide is amphoteric. Crystal are face centered cubic. Electron config. : [Kr] 4d8 5s1 Rhodium is a chemical element in the periodic table that has the symbol Rh and atomic number 45. A rare silvery-white hard transition metal, rhodium is a member of the platinum group, is found in platinum ores and is used in alloys with platinum and as a catalyst. Rhodium is a hard silvery white and durable metal that has a high reflectance. If slowly cooled from a red hot state it changes in air to the sesquioxide, which at higher temperatures converts back to the metal. Rhodium has both a higher melting point and lower density than platinum. It is not attacked by acids and only dissolves in aqua regia. ApplicationsThe primary use of this element is as an alloying agent for hardening platinum and palladium. These alloys are used in furnace windings, bushings for glass fiber production, thermocouple elements, electrodes for aircraft spark plugs, and laboratory crucibles. Other uses; It is used as an electrical contact material due to its low electrical resistance, low and stable contact resistance, and its high corrosion resistance. Plated rhodium, made by electroplating or evaporation, is extremely hard and is used for optical instruments. This metal finds use in jewelry and for decorations. It is also a highly useful catalyst in a number of industrial processes (notably it is used in the catalytic system of automobile catalytic converters and for catalytic carbonylation of methanol to produce acetic acid by the Monsanto process).
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