Title: Aluminum
CAS Registry Number: 7429-90-5
Additional Names: Aluminium
Literature References: Al; at. wt 26.9815386; at. no. 13; valence 3. Group IIIA (13). Naturally occurring isotope (mass number): 27 (100%); known artificial radioactive isotopes: 22-25, 26 (T½ 7.2´105 years, longest-lived known isotope, b+ and g emitter, found in meteors), 28-32. One of the most abundant metals in earth's crust: 8.3% by wt (83,000 ppm); occurs in nature primarily in combination with silica, also as oxide (see Aluminum Silicate; Aluminum Oxide). First obtained in impure form by Oersted in 1825; prepd as metal powder by Wöhler in 1827. Commercially important source is bauxite. Reviews of aluminum, its alloys and compds: Brandt, "Aluminum and Aluminum Alloys" in Proc. Met. Soc. Conf. vol. 40, E. D. Verink, Ed. (Gordon & Breach, New York, 1966); Aluminum 3 vols., K. R. Van Horn, Ed. (American Society for Metals, Metal Park, Ohio, 1967); Wade, Bannister, "Aluminum, Gallium, Indium and Thallium" in Comprehensive Inorganic Chemistry vol. 1, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 993-1064; Chemistry of the Elements, N. N. Greenwood, A. Earnshaw, Eds. (Pergamon Press, New York, 1984) pp 243-295; J. T. Stanley, W. Haupin in Kirk-Othmer Encyclopedia of Chemical Technology vol. 2 (John Wiley & Sons, 4th ed., 1992) pp 184-251; W. C. Sleppy et al., ibid. 252-345. Review of clinical toxicology: C. D. Hewitt et al., Clin. Lab. Med. 10, 403-422 (1990); of toxicology and human exposure: Toxicological Profile for Aluminum (PB99-166613, 1999) 393 pp. Book: Chemistry of Aluminum, Gallium, Indium and Thallium, A. J. Downs, Ed. (Blackie Academic & Professional, London, 1993) 515 pp.
Properties: Tin-white, malleable, ductile metal, with somewhat bluish tint; capable of taking brilliant polish which is retained in dry air. In moist air, oxide film forms which protects metal from corrosion. Available in bars, leaf, powder, sheets, or wire. d 2.70. mp 660°. bp 2327°. Does not vaporize even at high temps, but finely divided aluminum dust is easily ignited, and may cause explosions. Reacts with dil HCl, H2SO4, KOH and NaOH with evolution or hydrogen. Reduces the cations of many heavy metals to the metallic state E°(aq) Al3+/Al -1.66 V. Solns of Al3+ in dil HCl or neutral or slightly acid solns of most aluminum salts, yield with Na2S, a white ppt soluble in excess of Na2S. Dil neutral soln of aluminum salts yields white gelatinous ppt on boiling with sodium acetate.
Melting point: mp 660°
Boiling point: bp 2327°
Density: d 2.70
CAUTION: Potential symptoms of overexposure are irritation of eyes, skin and respiratory system. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 12. See also Patty's Industrial Hygiene and Toxicology vol. 2C, G. D. Clayton, F. E. Clayton, Eds. (John Wiley & Sons, New York, 4th ed., 1994) pp 1881-1902.
Use: As pure metal or alloys (magnalium, aluminum bronze, etc.) for structural material in construction, automotive, electrical and aircraft industries. In cooking utensils, highway signs, fencing, containers and packaging, foil, machinery, corrosion resistant chemical equipment, dental alloys. The coarse powder in aluminothermics (thermite process); the fine powder as flashlight in photography; in explosives, fireworks, paints; for absorbing occluded gases in manuf of steel. In testing for Au, As, Hg; coagulating colloidal solns of As or Sb; pptg Cu; reducer for determining nitrates and nitrites; instead of Zn for generating hydrogen in testing for As. Forms complex hydrides with lithium and boron, such as LiAlH4, which are used in preparative organic chemistry. |