A chemical equation represents the way in which reactants form to make new substances. An accurate chemical equation has the correct ratio of reactants and products called Coefficients. These are the numbers in front of the reactant or product.
Two principles to remember while writing a chemical equation:
1. Every chemical compound has a formula which cannot be altered.
2. A chemical reaction must account for every atom that is used. This is an application of the Law of Conservation of Matter which states that in a chemical reaction atoms are neither created nor destroyed.
To make a balanced equation,you need to adjust the number of units of some of the substances until you get equal numbers of each type of atom on both sides.