What is the chemical formula for aluminum?

Aluminum is an element and as such does not have a formula; its symbol is Al and atomic number is 13. The atomic mass of Al is 26.981539 amu and it is derived from bauxite.

Aluminum was discovered in 1825 by Hans Christian Oersted, and its name comes from the Latin "alumen." Aluminum foil is a common household item that is produced by oxidizing sheets of aluminum, or adding oxygen. The chemical formula for this process is: 4 Al(S) + 3 O₂ G &8658; 2 Al2)₃ (S).

Aluminum foil consists of both aluminum and a thin layer of aluminum oxide on the outside. When the foil is rolled up tightly, the inner side, which receives less exposure to oxygen in the air, remains shiny while the outside layer becomes duller.