What is the chemical equation of magnesium oxide?

When magnesium is burned in air, it burns with a bright, white flame. The product is a white powdery solid. This happens because at high temperatures the magnesium atoms in the metal combine with the oxygen atoms in the air. A chemical reaction produces magnesium oxide, powdery ash.

The reaction is given by 2Mg + O₂ → 2MgO

We see the white light of flame when magnesium burns because magnesium gets excited and move to a higher energy state which corresponds to white light, hence the colour of the flame is also white.