Transition metal, atomic number 13.
Aluminium (or aluminum; see different endings) is a chemical element in the boron group with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic, ductile metal. Aluminium is the third most abundant element (after oxygen and silicon), and the most abundant metal, in the Earth's crust.
Symbol Al. Atomic mass 26.98153857 u. Group 13, period 3. Electron configuration [Ne] 3s2 3p1. Electrons per shell 2, 8, 3. State at room temperature: Solid. Melting point 660.3 °C, boiling point 2469.8 °C. Discovered by unknown.
Element data from Wikipedia, CC BY-SA 3.0.