| Acid | (Arrhenius definition) any substance that, when dissolved in water, increases the concentration of hydronium ion, H30' (hydrogen ion, H'). (Bronsted-Lowry definition) the species (molecule or ion) that donates a proton to another species in a proton-transfer reaction. |
| Amphiprotic species | ta species that can act either as an acid or as a base |
| Anion | a negatively charged ion |
| Base | (Arrhenius definition) any substance that, when dissolved in.water, increases the concentration of hydroxide ion, OH-. (Bronsted-Lowry definition) The species (molecule or ion) that accepts a proton in a protontransfer reaction |
| Bronsted-Lowry concept | a concept of acids and bases in which an acid is the species donating a proton in a protontransfer reaction, whereas a base is the species accepting a proton in such a reaction |
| Cation | a positively charged ion |
| Hydronium ion | the H30' ion; also called the hydrogen ion and written H'(aq) |
| 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 |
| pH | the negative of the logarithm of the molar hydronium-ion concentration |
| Spectator ions | ions in an ionic equation that do not take part in the reaction |