The changes in the charge distribution induced upon solvation for a series of small anionic, neutral, and cationic species have been analyzed. The effect of solvent polarization on the solute wave function has been introduced from high-level ab initio self-consistent reaction field calculations. Determination of quantum molecular similarity measures allows us to quantify the redistribution of the charge density and the changes in Coulombic repulsions under the effect of hydration and establish some general trends depending on the electronic nature of the species.