Aluminum
Aluminum, or aluminium, is a silvery-white metal which has the atomic number 13. Its atomic weight is 26.98154 and its symbol is Al. Aluminum is the most abundant metal in the Earth's crust (8.1%), yet it does not occur naturally in any pure form. This accounts for its relatively late appearance as a popular metal.
Alum, a compound of aluminum and potassium, was used as an astringent, or binding, mineral salt as far back as Roman times. Louis Bernard Guyton de Morveau (1737-1816) recognized the base material in alum and called it alumine in 1761. Antoine-Laurent Lavoisier, in 1787, first raised the suspicion that alumine might be a new metal. The first attempt to produce aluminum was by Sir Humphry Davy in London in 1807. He succeeded in creating an alloy consisting of aluminum and iron. The name aluminium was proposed by Davy and accepted by most of the world. More than a hundred years later, in 1925, the American Chemical Society officially adopted "aluminum" as the proper spelling, making the United States differ from the rest of the world in usage.
The Danish physicist, Hans Christian Oersted, was the first to isolate aluminum in 1825. Oerstad was already known for his discoveries in electromagnetism. While a professor at the University of Copenhagen, he produced a small amount of aluminum by chemical process involving a dilute potassium amalgam (alloy containing mercury) to react with anhydrous aluminum chloride. In 1827, the German chemist Friedrich Wöhler repeated Oersted's experiments. For a long time it was thought that Wohler had been unsuccessful during this time; however, in 1920 unpublished notes were brought to light which proved that Wohler had found Oersted to be correct. Henri Sainte-Claire Deville (1818-1881), professor at the Ecole Normale in Paris, first used the electrolytic process to isolate aluminum in 1854. Using the methods of Oersted and Wohler, but substituting potassium with sodium, Sainte-Claire Deville succeeded in producing a fifteen-pound ingot of aluminum in 1855. By 1859, the price of aluminum had fallen from 3,000 francs to 300 francs per pound owing to Sainte-Claire Deville's process. This translates to about $500 to $5 per pound. Robert Bunsen, also known for invention of the Bunsen burner in 1837, conducted experiments isolating aluminum from magnesium chloride through electrolysis at the University of Heidelberg. His work paralleled Sainte-Claire Deville's. Bunsen published his findings one week before Deville presented a paper on his in Paris.
The electrolytic process was first attempted for aluminum production in 1886, discovered simultaneously by Paul Louis Toussaint Heroult (1863-1914) and Charles Martin Hall3 (1863-1914). The ore used by Heroult and Hall to extract their aluminum was cryolite, a sodium aluminum fluoride found in Greenland. Commercial production shifted to bauxite with development of the Bayer extraction process by Karl Joseph Bayer in 1886.
Aluminum has many properties that make it attractive for a variety of applications. It is malleable, highly ductile, light-weight, durable, nonmagnetic, nonsparking, nontoxic, and a good conductor of electricity. It is also visually attractive, with a bright silvery shine. It is now second only to steel as the world's most economically important metal, overtaking copper in 1957 on the basis of tonnage and value in trade. The only factor that puts steel ahead of aluminum in industrial use is the load-bearing ability of steel for construction and heavy industries.
The use of aluminum accelerated during the latter half of the twentieth century. It has become part of modern life. It was first widely used during World War II for military purposes. Since then, it has been used in cookware, cooking foil, furniture, packaging, door and window frames, picture frames, piping, and poles. It is used extensively in the aircraft and spacecraft industries. Although its electrical conductivity is only 60 percent that of copper, it is popular in wiring because it is cheap and light-weight. In addition, aluminum is also used as an ingredient in antiperspirants, as a mordant for dyes and as a treatment for stomach ulcers.
Since the initial explorations by a few individuals some two hundred years ago, aluminum has become a common commodity in households and industry.
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