When the magnesium metal burns it reacts with oxygen found in the air to form Magnesium Oxide. ... Oxygen and magnesium combine in a chemical reaction to form this compound. After it burns, it forms a white powder of the magnesium oxide. The magnesium ribbon burns with a dazzling light and magnesium oxide is formed and it is in white colour. The bright light results because this reaction produces a lot of heat.
2Mg(s)+O2(g)→2MgO(s)+energy