![]() ![]() When it is exposed to the air, a thin layer of aluminum oxide is formed on the surface of the metal. Pure aluminum is a very reactive element and is rarely found on Earth in its free form.Īluminum acts as an excellent conductor of electricity and heat, but is non-magnetic. In standard conditions aluminum is a fairly soft, strong, and lightweight metal. There are 3 valence electrons in the outer shell. Aluminum atoms contain 13 electrons and 13 protons. It is classified as a post-transition metal and a "poor metal". Discovered by: Hans Orsted in 1825, first isolated by Friedrich Wohler in 1827Īluminum is the second element in the thirteenth column of the periodic table.Copyright © 2023, Columbia University Press. The Columbia Electronic Encyclopedia, 6th ed. The process depends critically on the availability of cheap hydroelectric power. Hall, a student at Oberlin College, and Paul Héroult, a French metallurgist. However, it was not until 1886 that the process by which aluminum is produced today was discovered independently by C. Sainte-Claire Deville first prepared inexpensive pure metal in 1854 and set about perfecting a process for its commercial production. Oersted succeeded in obtaining impure aluminum in 1825, but Friedrich Wöhler had greater success and is usually credited with its first isolation, in 1827. recognized aluminum as the metal and alumina as its oxide. Sir Humphry Davy and other chemists in the early 19th cent. The Romans used various aluminum compounds as astringents they called these alum. Important alloys of aluminum include duralumin, aluminum bronze, and aluminum-magnesium they are used extensively in aircraft and other industries.Īlthough the metal was not isolated until the 19th cent., use of aluminum compounds originated in antiquity. The development of methods for coloring aluminum led to its use in jewelry, on wall surfaces, and in colored kitchenware. A mixture of powdered aluminum and iron oxide, called thermite, is used in welding because of the large amount of heat liberated when it is ignited. The anode is consumed as it combines with the oxygen to form carbon dioxide.Īluminum foil is used as a wrapping material. Molten aluminum collects at the bottom of the tank, and oxygen is liberated at the anode. In an electric furnace an iron tank lined with carbon serves as the cathode and large blocks of carbon serve as the anode the electric current generates enough heat to keep the cryolite melted. Commercially, aluminum is prepared by the Hall-Héroult process, which consists essentially of the electrolysis of alumina prepared from bauxite and dissolved in fused cryolite. It is rapidly attacked by alkalies (such as lye) and by hydrochloric acid.Īlthough it is the most abundant metal in the earth's crust (about 8% by weight), aluminum does not occur uncombined but is an important constituent of many minerals, including clay, bauxite, mica, feldspar, alum, cryolite, and the several forms of aluminum oxide (alumina) such as emery, corundum, sapphire, and ruby. Although it is chemically very reactive, aluminum resists corrosion by the formation of a self-protecting oxide coating. Although less conductive than copper wire of the same diameter, aluminum wire is often used for high-tension power transmission because it is lighter and cheaper. The pure metal is soft, but it becomes strong and hard when alloyed. It is ductile, malleable, and an excellent conductor of heat and electricity. It is a member of Group 13 of the periodic table. 2.6989 at 20☌ valence +3.Īluminum is a silver-white metal with a face-centered cubic crystalline structure. ![]() Aluminum əlo͞o´mĭnəm, called in British countries aluminium ăl˝yo͞omĭn´ēəm, metallic chemical element symbol Al at. ![]()
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