Time： 2018-05-03 09:05:02
Aluminium or aluminum is a chemical element with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic and ductile metalin the boron group. By mass, aluminium makes up about 8% of the Earth's crust; it is the third most abundant element after oxygen and siliconand the most abundant metal in the crust, though it is less common in the mantle below. The chief ore of aluminium is bauxite. Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is found combined in over 270 different minerals.
Aluminium is the most abundant metal in the Earth's crust. It makes up about 8% by weight of the Earth's solid surface. The highest concentration of aluminium oxide is found in ore bauxite. Pure aluminum is obtained by extracting alumina from the bauxite. By means of an electrolytic bath, 1 kg of pure aluminium is obtained from 1.9 kg alumina.