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| Atomic Number: | 13 | Atomic Symbol: | Al | | Atomic Weight: | 26.98154 | Electron Configuration: | 2-8-3 | | Shells: | 2,8,3 | Filling Orbital: | 3p1 | | Melting Point: | 660.37oC | Boiling Point: | 2467oC | | Uses: | aluminium cans, airplanes and many others |
History(L. alumen, alum) The ancient Greeks and Romans used alum as an
astringent and as a mordant in dyeing. In 1761 de Morveau proposed the name
alumine for the base in alum, and Lavoisier, in 1787, thought this to be the
oxide of a still undiscovered metal.
Wohler is generally credited with having isolated the metal in 1827, although
an impure form was prepared by Oersted two years earlier. In 1807, Davy proposed
the name alumium for the metal, undiscovered at that time, and later agreed to
change it to aluminum. Shortly thereafter, the name aluminium was adopted to
conform with the "ium" ending of most elements, and this spelling is now in use
elsewhere in the world.
Aluminium was also the accepted spelling in the U.S. until 1925, at which
time the American Chemical Society officially decided to use the name aluminum
thereafter in their publications.
SourcesThe method of obtaining aluminum metal by the electrolysis of
alumina dissolved in cryolite was dicovered in 1886 by Hall in the U.S. and at
about the same time by Heroult in France. Cryolite, a natural ore found in
Greenland, is no longer widely used in commercial production, but has been
replaced by an artificial mixture of sodium, aluminum, and calcium fluorides.
Aluminum can now be produced from clay, but the process is not economically
feasible at present. Aluminum is the most abundant metal to be found in the
earth's crust (8.1%), but is never found free in nature. In addition to the
minerals mentioned above, it is found in granite and in many other common
minerals.
PropertiesPure aluminum, a silvery-white metal, possesses many
desirable characteristics. It is light, it is nonmagnetic and nonsparking,
stands second among metals in the scale of malleability, and sixth in ductility.
UsesIt is extensively used for kitchen utensils, outside building
decoration, and in thousands of industrial applications where a strong, light,
easily constructed material is needed.
Although its electrical conductivity is only about 60% that of copper, it is
used in electrical transmission lines because of its light weight. Pure aluminum
is soft and lacks strength, but it can be alloyed with small amounts of copper,
magnesium, silicon, manganese, and other elements to impart a variety of useful
properties.
These alloys are of vital importance in the construction of modern aircraft
and rockets. Aluminum, evaporated in a vaccum, forms a highly reflective coating
for both visible light and radiant heat. These coatings soon form a thin layer
of the protective oxide and do not deteriorate as do silver coatings. They are
used to coat telescope mirrors and to make decorative paper, packages, toys.
CompoundsThe compounds of greatest importance are aluminum oxide, the
sulfate, and the soluble sulfate with potassium (alum). The oxide, alumina,
occurs naturally as ruby, sapphire, corundum, and emery, and is used in
glassmaking and refractories. Synthetic ruby and sapphire are used in lasers for
producing coherent light.
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