Aluminium (British English) or aluminum (American English) is a chemical element, having the chemical symbol Al. Its atomic number (the number of protons) is 13. It has a standard atomic weight of 26.98154 g•mol −1, and is typically found as a solid in its elemental form.
Aluminium is considered to be a member of the "Post-transition metal" class of element. At a pressure of 101.325 kPa, it has a boiling point of 2,519 °C, and a melting point of 660.32 °C. It is the most reactive post-transition element metal and the most abundant metal in the Earth's crust. With a density of 2.70 g/cc, it is much lighter than other common metals such as copper and iron--see benchmark quantities for a comparison.
- Note: The form used by the International Union of Pure and Applied Chemistry