Aluminum was discovered in 1827. It is a soft, light, silvery-coloured metal. Its surface has a strongly adhering layer of oxide which protects the metal from corrosion. Aluminum is the third most abundant element in the earth's crust after oxygen and silicon.

Aluminum occurs in the mineral bauxite (a mixture of the oxides of aluminum, iron and silicon). Bauxite occurs in large quantities in tropical and sub-tropical countries. The Aluminum Company of Canada (ALCAN) obtains most of its supply of raw material from Jamaica in the form of alumina (Al₂O₃).

One of the metal's most valuable properties is its corrosion resistance. This, together with its light weight, makes it an ideal construction material for the building and the automotive industries. An electrolytic process called anodizing can increase the corrosion resistance of the metal. The electrical conductivity is about two-thirds of copper, making it economical for power transmission. Other uses of aluminum include its use:

• as an alloying element with magnesium, manganese, silicon, and zinc.
• in special paints,
• as tubes and containers,
• as packing foil,
• as a catalyst.

Common aluminum compounds are:

• aluminum chloride, AlCl₃, which is used as a catalyst in the manufacture of synthetic rubbers in the U.S. during World War II.
• aluminum chlorohydrate, AlCl₃.H₂O, a topical antiperspirant or body deodorant which acts by constricting the pores, thus inhibiting water loss.
• aluminum fluoride, AlF₃, an additive to the molten electrolyte of the aluminum production cell in order to lower the melting point and increase the electrical conductivity.
• aluminum hydroxide, Al(OH)₃, which is used as a foaming agent in fire extinguishers and as a mordant in dyeing.
• corrundum, aluminum oxide (Al₂O₃), which is one of the hardest minerals. Gemstones such as ruby and sapphire are essentially aluminum oxide with appropriate doping with other metals. These gemstones are used as laser crystals and in other solid state devices.
• aluminum sulfate, Al₂(SO₄)₃, which is used in sizing and coating papers, as a flocculating agent in the purification of water and sewage, and as mordant in texture dyeing.

BCIT Chemistry Resource Center
http://nobel.scas.bcit.ca/resource/