What causes the two atoms to combine to form a bond which is:
(i) Non-polar
(ii) Polar-covalent and
(iii) Ionic in nature?
The nature of the bond between the two atoms depends on upon the electronegativity difference in them.
(i) If the two atoms are identical or have the same electronegativity (C and S), the bond is of non-polar nature.
(ii) If the two atoms differ in electronegativity, but the difference is less than 1 -9, the bond is mainly polar covalent with little ionic character. For example, the bond between carbon and chlorine.
(iii) If the difference in electronegativity of two atoms is more than 1 -9, the percentage ionic character is more than the percentage polar covalent character. Larger the electronegativity difference, greater will be the ionic character. For example, the bond between sodium and fluorine is completely ionic.
