Period 3 element fresh mineral waters. "Aluminium" (symbol Al) or "aluminum" (American English) is a silvery white member of the boron group of chemical elements and a post-transition metal. It is not soluble in water under normal circumstances. Aluminium is the third most abundant element (after oxygen and silicon), and the most abundant metal, in the Earth's crust. It makes up about 8% by weight of the Earth's solid surface. Aluminium metal is too reactive chemically to occur natively. Instead, it is found combined in over 270 different minerals. The chief ore of aluminium is bauxite. Aluminium is remarkable for the metal's low
Period 5 element Like the other halogens, free iodine occurs mainly as a diatomic molecule I, and then only momentarily after being oxidized from iodide by an oxidant like free oxygen. In the universe and on Earth, iodine's high atomic number makes it a relatively rare element. However, its presence in ocean water has given it a role in biology (see below). Xenon is a chemical element with the symbol Xe and atomic number 54. A colorless, heavy, odorless noble gas, xenon occurs in the Earth's atmospherein trace amounts. Although generally unreactive, xenon can undergo a few chemical reactions such as the formation