Diatomic elements 		To remedy the situation we need to balance the reaction. In order to do this, we place numbers (coefficients) in front of the symbols. For example:

2 H2 + O2 → 2 H2O

Less frequently, fractions may be used to simplify the balancing of an equation involving a diatomic element: 

H2 + ½ O2 → H2O

The Rules:  To balance a reaction you must:
  • know the correct formulas for the reactants and products
  • use coefficients to make the same number of each type of atom on each side