First, let's take a look at what happens when a
nonelectrolyte is being dissolved. Essentially what's happening there is that the
molecules of AB are being split apart from one another and surrounded by water molecules.
So that's the overall change.
Weak Electrolytes
Next let's consider what happens with a weak electrolyte,
again a molecular material. When the weak electrolyte goes into solution, a few molecules
will dissociate into ions but most of the molecules stay together. Molecules which
dissolve in water are polar molecules, so there will be dipole-dipole, or possibly even
hydrogen bonding, between the solute and the solvent. For the molecules which do
dissociate into ions, you will have ion-dipole attractions.
Strong Electrolytes
Next let's consider an ionic compound, a strong electrolyte.
Here, the ions in the solid are being broken apart, being pulled away from the solid,
being pulled away from the other ions, and are being surrounded by water molecules. The
polarity of water molecules is a very important factor here. There are several water
molecules around each ion in solution. The positive ions are surrounded by several water
molecules, each of which has the negative oxygen end of the water molecule pointed toward
the positive ion. Around the negative ions, the positive hydrogen ends of the water
molecules are pointed toward the ions. The interaction or attraction between an ion and a
polar molecule is called an ion-dipole bond.
