Electronegativity determines the bond with the most covalent character.
The greater the electronegativity distinction, the more ionic a bond is. Smaller electronegativity determines the bond with the most covalent character variations create a more covalent bond. Therefore, it has to be determined which molecule has the most comparable electronegative atoms.
The form of bond is predicated on the electronegativity difference of the two atoms involved in the bond.
Hence, by measuring the difference in electronegativity between the two atoms involved in the bond, the degree to which a given bond is ionic or covalent is calculated.