Shortly: because the ions already present in ionic compounds are soluble in water due to their electric charge. read more
Most ionic compounds are soluble in water because the electrostatic forces of the polar water molecules are stronger than the electrostatic forces keeping the ions together. There are several exceptions, however, where the electrostatic forces between the ions in an ionic compound are strong enough that the water molecules cannot separate them. read more
Whereas ionic compounds are more soluble (in the terms above described) the covalent compounds are also soluble. But this is true in a certain sense: the more polar the molecule is (not only the bonds) the more they are soluble in water, and vice-versa. read more
Ionic compounds are more reactive than molecular compounds. The enthalpy of fusion (heat energy absorbed when a solid melts) and enthalpy of vaporization (heat energy absorbed when a liquid boils) are higher in ionic compounds. read more