Page 12 - Curriculum Visions Dynamic Book

Rhodium (Rh)
Element 45.A rare, brilliantly lustrous, silvery-white member of the transition metals in the Periodic Table. Rhodium is a precious metal and will not tarnish. It melts at a higher temperature than platinum and is less dense. It is also very
hard and resists wear. Rhodium is insoluble in normal acids.
Discovery
Rhodium was discovered by William Hyde Wollaston in England in 1803.
Technology
Its main use is as an alloying metal to make platinum harder. It is often electroplated as a coating on other metals to give a shiny, non-tarnishing finish to tableware and jewellery. It makes the reflector surface
in searchlight mirrors. It is also used as
a catalyst to speed up chemical reactions in carbon chemistry, including in motor vehicle exhaust systems.As a hardened alloy, it makes bushes for motors and it is also used for laboratory crucibles.
Geology
It occurs as a native element in tiny quantities in ores containing copper and nickel. Rhodium does not combine in nature to produce many minerals, but sometimes it appears as
a natural alloy with platinum, iridium and osmium. Rhodium is normally obtained as a by-product of the refining of copper and nickel.
Biology
Rhodium is not found in living things.
Key facts...
Name: rhodium
Symbol: Rh
Atomic number: 45
Atomic weight: 102.9
Position in Periodic Table: transition metal, group
(9) (cobalt group); period 5. Precious metal State at room temperature: solid
Colour: silvery-white
Density of solid: 12.4 g/cc
Melting point: 1,966°C
Boiling point: 3,727°C
Origin of name: from the Greek word rhodon,
meaning rose for the red colour of some of its
compounds such as rhodium chloride Shell pattern of electrons: 2–8–18–16–1
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