Platinum

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Platinum

This is platinum.

Symbol Pt
Atomic number 78
Atomic mass 195.09 amu

Platinum, discovered in 1735, was given the name which was taken from the Spanish, platina, meaning little silver.

Distinguishing properties

Platinum is described as a silvery-white, dense metal that is quite malleable and ductile when pure. Platinum is resistant to oxidation and tarnish and does not react with most acids. It dissolves readily in aqua regia. Platinum is one of the heaviest elements, with a density of 21.45 g/cc, almost twice that of lead.

Occurrence

Platinum is recovered from deposits in its elemental form. In these deposits, the platinum is most often mixed with other metals such as gold, copper, nickel, iridium, osmium, palladium, ruthenium, and rhodium. Shown in the image is an unusually large nugget (1.1 kilogram) of platinum found in the Ural Mountains, USSR. Platinum also occurs in minerals sperrylite (as platinum arsenate) and cooperite (as platinum (II) sulfide).

Usage

Platinum is an important metal. It is used:

  • in the manufacture of laboratory instruments, medical and dental instruments,
  • as electrical contacts,
  • as electrode material in electrochemistry,
  • in catalytic converters in auto exhaust systems,
  • in hyperdermic needles. An alloy of platinum containing up to 30% iridium is usually used for this application. Iridium content increases hardness and resistance to chemical attack.
  • as a catalyst when used in the powder form (platinum black).
  • in jewellry.

See also

Periodic table of the elements