Illustrated Glossary of Organic Chemistry

Solvation: The process of becoming associated with solvent molecules, and of becoming surrounded by a solvent shell.

Liquid phase

Solid phase

NaCl completely undissolved.
NaCl begins to dissolve.
Partial solvation of one Cl- has occurred.

NaCl completely dissolved.
Complete solvation.
Dissolution of NaCl into water requires solvation. In solid NaCl, the Na+ cation and Cl- anion are associated via ionic bonding (an electrostatic interaction). In the crystal lattice Na+ is surrounded by numerous Cl- and other Na+, but not by solvent. For the NaCl to dissolve and migrate away from the crystal lattice, each ion must be attracted to (by electrostatic interaction) water molecules. When enough water molecules have been attracted the ion has a solvent shell (it is now solvated), and the ion dissolves. The electrostatic attraction is indicated by |||||||. (The illustration has been simplified for clarity. In aqueous solution the actual number of water molecules surrounding each Na+ and Cl- is greater than shown in the diagram.)