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| Atomic Number: | 45 | Atomic Symbol: | Rh | | Atomic Weight: | 102.9055 | Electron Configuration: | 2-8-18-16-1 | | Shells: | 2,8,18,16,1 | Filling Orbital: | 4d8 | | Melting Point: | 1966oC | Boiling Point: | 3727oC | | Description: | Hard silvery white metal | | Uses: | Used as a coating to prevent wear on high quality science
equipment and with platinum to make thermocouples. Also used for headlight
reflectors. |
History(Gr. rhodon, rose). William Wollaston of England discovered
rhodium in 1803-4 in crude platinum ore he presumably obtained from South
America.
SourcesRhodium occurs native with other platinum metals in river sands
of the Urals and in North and South America. It is also found with other
platinum metals in the copper-nickel sulfide area of the Sudbury, Ontario
region. Although the quantity occurring here is very small, the large tonnages
of nickel processed make the recovery commercially feasible. The annual world
production of rhodium is only 7 or 8 tons.
Properties- The metal is silvery white and at red heat slowly changes in air to the
resquioxide.
- At higher temperatures it converts back to the element.
- Rhodium has a higher melting point and lower density than platinum.
Uses- Its primary use is as an alloying agent to harden platinum and palladium.
- Such alloys are used for furnace windings, thermocouple elements, bushings
for glass fiber production, electrodes for aircraft spark plugs, and laboratory
crucibles.
- It is useful as an electrical contact material as it has a low electrical
resistance, a low and stable contact resistance, and is highly resistant to
corrosion.
- Plated rhodium, produced by electroplating or evaporation, is exceptionally
hard and is used for optical instruments.
- It has a high reflectance and is hard and durable.
- Rhodium is also used for jewelry, for decoration, and as a catalyst.
HandlingExposure to rhodium (metal fume and dust, as Rh) should not
exceed 1 mg/m^3 (8-hour time-weighted average, 40-hour week).
CostsRhodium costs about $1,000/troy oz.
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