| Half-reaction | one of two parts of a redox reaction, one of which involves a loss of electrons and the other of which involves a gain of electrons |
| Ionic equation | a chemical equation for a reaction involving ions in solution in which soluble substances (ones that dissolve readily) are represented by the formulas of the predominant species in that solution |
| Oxidation | the part of an oxidation-reduction reaction in which there is a loss of electrons by a species or an increase in the oxidation number of an atom |
| Oxidation number | the charge an atom in a substance would have if the pairs of electrons in each bond belonged to the more electronegative atom |
| Oxidation-reduction reaction (redox reaction) | a reaction in which electrons are transferred between species or in which atoms change oxidation number |
| Reduction | the part of an oxidation-reduction reaction in which there is a gain of electrons by a species or a decrease of oxidation number of an atom |
| Spectator ions | ions in an ionic equation that do not take part in the reaction |