1. In chemistry Ion-association is a chemical reaction whereby ions of opposite electrical charge come together in solution to form a distinct chemical entity.
2. Ion-associates are classified according to the number of ions that associate with each other, and the nature of the interaction.
3. The most important factor to determine the extent of ion-association is the dielectric constant of the solvent.
4. Ion-associates have been characterized by means of vibrational spectroscopy.
5. The concept has been proposed by Niels Bjerrum.