Polarizing power of the cation depends on its size and the charge present on it. The smaller the size and the higher the charge of the cation, the greater the polarizing power. Among `Na^(+)`, `Mg^(+2)` and `Al^(+3)`, `Al^(+3)` has least ionic size and the charge present on it is maximum. Hence, polarizing power of `Al^(+3)` is maximum. Among the halides `AlF_(3)` is ionic, but other halides of aluminium are covalent. Polarizing power of magnesium is less than aluminium. Hence, chloride and fluoride of magnesium are ionic. But `Na^(+)` has the least polarizing power. Hence, all the haldies of sodium are ionic.
