Let's compare NaCl and AlCl3. Step 1: Look at the cations. Na has a charge of +1. Al has a charge of +3. Step 2: Look at their sizes. Al+3 is much smaller than Na+. Step 3: Apply the rule. Since Al+3 is smaller and has a higher positive charge (+3), it has a much higher 'polarizing power'. Step 4: Outcome. Al+3 pulls the electron cloud of the Chloride (Cl-) ion very strongly. This turns the ionic bond into a covalent bond. Result: AlCl3 has more covalent character than NaCl.