Question

explain why ionic substances show a wide range of solubilities in water

Answer 1

For dissolving an ionic compound in a solvent like the water molecules, it must be sufficient to stabilize the ions which result from breaking of the ionic bond. Since water is a polar molecule and it has a permanent dipole. The O atom of the water molecule has a partial negative charge and H atoms have usually a partial positive charge. When an ionic substance is placed in water, the water molecules attract the cation and anions ions from the crystal. As a result of this, the ionic particles are then free to move around within the solution. The cations have several water molecules around them and all the O atoms of the solvent will close to the positive ion of the ionic compound. While the anions have several water molecules around them and all the H atoms of the solvent will close to the negative ion of the ionic compound. Furthermore, the "shell" of water molecules around the ionic compound will reduce the attractions between the ions.