Page 19 - Curriculum Visions Dynamic Book

Discovery
It was discovered in 1825 by Hans Christian Oersted in Denmark. He reacted aluminium chloride (AlCl3) with a potassium amalgam (an alloy of potassium and mercury). It formed an aluminium amalgam (and potassium chloride). By heating the aluminium amalgam, the mercury boiled off, and aluminium was left.
Technology
Alum was used by ancient civilizations
for stabilising dyes (alum is a mordant). Aluminium metal is now used as a packaging material (cooking foil, soft drink cans and so on), for window frames, and cooking pans (often with a non-
stick inner surface). It is widely applied in the building industry as a structural material where lightness and resistance to corrosion are important. It also appears in high-tension electricity cables because it is much lighter and cheaper than copper (an even better conductor).Aluminium is used for lightness in engines, aircraft and spacecraft.Aluminium can be evaporated in a vacuum and then can coat other substances, making a decorative and corrosion-resistant surface. It is a good reflector of radiant heat.
Geology
Aluminium makes up about 8% by weight of the Earth’s crust. It is found in most minerals. However, it is only commercially mined from its hydrated oxide, the mineral bauxite (Al2O3.2H2O).This soft subsurface material occurs in tropical soils, together with iron oxides.When hardened in a soil, such material is called laterite.
Some oxides of aluminium are precious stones (gemstones), such as ruby (red) and
sapphire (blue), as well as hard abrasive materials such as emery and corundum.
Aluminium is found in most soils as part of the clay minerals.
Biology
Aluminium compounds are not an essential part of living things; and although not harmful in small quantities, aluminium can be toxic if taken in over a long period of time.The use of aluminium pans (with no non-stick liner) may be one way in which people can ingest aluminium, which builds up in the body. Alzheimer’s disease may be a disease linked to aluminium poisoning.
Acid rain mobilises aluminium compounds in the soil.They then are absorbed by plant roots and taken into the plants, where they cause death.The acid rain/aluminium relationship is the main result of acid rain.
Aluminium is highly reflective and is cheaper to produce than many other similar metals.As a result, it
can be used on a large scale, such as in the mirrors of this solar generating plant.
Rubies are prized gemstones.They are made mainly of aluminium
and oxygen (aluminium oxide).
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