Chemical reactions in aqueous solution that involve ionic reactants or products may be represented more realistically by complete ionic equations and, more succinctly, by net ionic equations Formulas for the substances undergoing the change (reactants) and substances generated by the change (products) are separated by an arrow and preceded by integer coefficients indicating their relative numbers.

Balanced equations are those whose coefficients result in equal numbers of atoms for each element in the reactants and products. A large number of important reactions are included in three categories: precipitation, acid-base, and oxidation-reduction (redox).

stoichiometry — relationships between the amounts of reactants and products of a chemical reaction. complete ionic equation — chemical equation in which all dissolved ionic reactants and products, including spectator ions, are explicitly represented by formulas for their dissociated ions. net ionic equation — chemical equation in which only those dissolved ionic reactants and products that undergo a chemical or physical change are represented (excludes spectator ions). precipitation reaction — reaction that produces one or more insoluble products; when reactants are ionic compounds, sometimes called double-displacement or metathesis.