Summary and Key Ideas
Writing and Balancing Chemical Equations
Chemical equations are symbolic representations of chemical and physical changes. 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. 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.
chemical equation with equal numbers of atoms for each element in the reactant and product
symbolic representation of a chemical reaction
number placed in front of symbols or formulas in a chemical equation to indicate their relative amount
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
chemical equation in which all reactants and products are represented as neutral substances
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)
substance formed by a chemical or physical change; shown on the right side of the arrow in a chemical equation
substance undergoing a chemical or physical change; shown on the left side of the arrow in a chemical equation
ion that does not undergo a chemical or physical change during a reaction, but its presence is required to maintain charge neutrality