The exterior of magnesium metal is shielded with a thin layer of oxide that somewhat protects the metal from attack by air. Magnesium metal burns in air with a distinctive blinding bright white spark when ignited to give a mixture of white magnesium oxide, MgO, and magnesium nitride, Mg3N2. Magnesium is highly reactive to halogens such as chlorine, Cl2 or bromine, Br2, and it burns to create dihalides magnesium chloride, MgCl2 and magnesium bromide.
