ALUMINUM (AL)

last update 01 sep 10

* Aluminum is a member of the main group metals family:

main group metals in the periodic table

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   ALUMINUM / Al / 13

   A soft, malleable, silvery, fairly reactive metal.  One isotope
   occurs in nature, Al<17/13>; it is stable.

     atomic weight:       26.981538
     abundance:           3rd
     density:             2.6989 g/cc
     melting point:       660 C      
     boiling point:       2,467 C
     valence:             3
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Aluminum is arguably the second most industrially important metal, after iron. It is found mostly in the form of bauxite ore, AlO(OH), and is refined by an energy-intensive electrolytic process. Tens of millions of tonnes are produced each year, with about the same amount recycled. With rising energy costs, aluminum recycling is becoming more important.

Of course, aluminum is of major importance as a structural material, particularly for aircraft where its high strength-to-weight ratio comes in handy, and is also used for electrical wiring; copper has better conductivity, but it is more expensive. Aluminum sulfate -- Al2(SO4)3+16H2O -- is used on a wide scale for paper treatment and water purification. When small amounts of lime (CaOH) and aluminum sulfate are introduced into cloudy water, they react to form aluminum hydroxide, which precipitates down to the bottom, carrying the impurities along with it.

Incidentally, outside America aluminum is usually called "aluminium", really a more appropriate name for a metal. There are various contradictory stories as to how this divergence in usage came about; since it doesn't amount to a particularly important issue, there's no particular reason to try to sort them out, and we might as well just accept the difference in usage.