The equation which describes the chemical change taking place in the reaction is said to be a word equation for molecules. In order to write the word equation for a reaction, the reactants are always written on left side of the arrow, \(\rightarrow\) and products are written on the right side. \(+\) sign is used to show the addition of two or more elements or compounds in reactants side to form product. One or more product can form during a reaction and are separated by \(+\) sign.
Since, magnesium and oxygen are reactants so, they are written on the left side of the \(\rightarrow\) and are separated by \(\+\). The magnesium oxide is formed that is it is product in the reaction so it is written on the right side of the \(\rightarrow\) .
Hence, the word equation for molecules of magnesium reacting with molecules of oxygen to produce molecules of magnesium oxide is magnesium \(+\) oxygen \(\rightarrow\) magnesium oxide.
