aluminum (É™lÅ«'mÄ*nÉ™m) , called in British countries aluminium (ăl'yÅ«mÄ*n'Ä“É™m) , metallic chemical element; symbol Al; at. no. 13; at. wt. 26.98154; m.p. 660.37°C; b.p. 2,467°C; sp. gr. 2.6989 at 20°C; valence +3.


Aluminum is a silver-white metal with a face-centered cubic crystalline structure. It is a member of group IIIa of the periodic table. It is ductile, malleable, and an excellent conductor of heat and electricity. The pure metal is soft, but it becomes strong and hard when alloyed. 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. Although it is chemically very reactive, aluminum resists corrosion by the formation of a self-protecting oxide coating. It is rapidly attacked by alkalies (such as lye) and by hydrochloric acid.