Copper

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Copper

This is copper.

Symbol Cu
Atomic number 29
Atomic mass 63.546 amu

Copper, known to mankind since the ancient times, is widely distributed as sulfides, arsenides, chlorides, and carbonates, in combination with iron and other transition elements. Copper is a reddish metal with a high luster. It and gold are the only two coloured metals. The metal is soft, ductile and it is very high thermal and electrical conductivity. The surface of copper is often dulled by oxide formation.

Forms

The two main classes of copper ores are:

  1. the mixed sulfides of copper and iron, such as chalcopyrite CuFeS2, and bornite Cu5FeS4.
    • Chalcopyrite
      Chalcopyrite is copper iron sulfide, and is the most common copper mineral. It has a brassy yellow colour, but tarnishes. There are large deposits in Norway, Germany, Bosnia, Serbia, Italy, and Spain.
    • Bornite
      Bornite is bluish-purple in color. It is a common copper ore, usually together with chalcopyrite.
  2. the basic carbonates such as azurite Cu3(CO3)2(OH)2, and malachite, Cu2CO3(OH)2.
    • Azurite
      Azurite
      Azurite is a deep-blue mineral found as a secondary mineral in copper deposits. It is often found with malachite. It is occasionally used ornamentally.
    • Malachite
      Malachite is one of the ores of copper. It usually occurs as a green crust on other copper minerals. It is used as an ornamental stone. It is found worldwide. Some of the largest deposits are found in the Ural mountains of Russia, Australia, Zaire, Zambia, and Chile.

Treatment of azurite and malachite with sulfuric acid produces copper sulfate, which has a characteristic blue colour.

Occurrence

In Canada, the main deposits of copper ore are found, associated with nickel, in the Sudbury region of Ontario. Copper is also found in various parts of British Columbia and in many other provinces. It is usually associated with other metals such as: gold, silver, zinc, molybdenum and lead.

In Canada, copper is refined by Noranda Ltd. in Montreal and INCO in Sudbury. The combined capacity of these two refineries is over 600,000 tonnes per year (worth about $1.3 billion/year). Impure copper is refined electrolytically. The electrolytic copper is 99.96 to 99.99% pure.

Usage

Uses of copper include:

  1. the use of weapons made with bronze in ancient times.
  2. coins such as "copper" pennies are made of bronze.
  3. coins such as dimes, nickels, and quarters contain an alloy of 30% nickel and 70% copper.
  4. the manufacture of ornaments, utensils made of brass.
  5. alloys of copper used in 14-carat gold, sterling silver jewelry and silverware.
  6. the manufacture of electrical wires and electrical components.
  7. roofing, the chalky green color of weathered copper (remember the green rooftop of Vancouver Hotel) is due to the formation of the basic carbonate, Cu(OH)2·CuCO3.
  8. water pipes in plumbing as it does not react with hot or cold water in an appreciable rate, and
  9. the need of trace amounts of copper by human. Current theories suggest that copper deficiency causes anemia because copper is needed for the absorption and mobilization of iron required to make hemoglobin. Important dietary sources of copper are nuts, liver and shellfish.
  10. the need of copper in certain marine animals. Copper serves this same oxygen-carrying function in the fluids of marine animals much the same way that iron is needed in higher animals.

Common compounds

The most common form of copper sulfate is the pentahydrate, CuSO4.5H2O, and has a wide variety of uses such as:

  • providing a source of trace amounts of copper when mixed with superphosphate to improve crop yield
  • an algicide (in quantities of <1 part per million) as it is toxic to micro-organisms in reservoirs and swimming pools
  • removal of mercaptans with a process known as "copper sweetening" in the petroleum refining process
  • in the manufacture of synthetic rayon fibres
  • in the tanning of leather
  • an electrolyte in copper-plating processes
  • a wood preservative

See also

Periodic table of the elements

External link

Examples of weathered copper known as patina: