Why are ionic compounds soluble in water while metals and covalent compounds are insoluble in water?
A compound will only dissolve in another if strong intermolecular attractions can be formed between the particles of the two compounds. Ionic compounds dissociate into ions when placed into aqueous solution; these ions can be strongly hydrated which lowers the energy significantly. On the other hand, nonpolar covalent compounds cannot bond strongly to water, and yet in order to dissolve the water molecules would have to be pushed apart to make room for the other ones, which would weaken the interactions between water molecules and raise the energy. Therefore, solvation does not occur. The same goes for metals – water molecules cannot effectively bond to neutral metal atoms.
