The bond is considered to be more polar as the difference in electronegativity between the two atoms increases. Electronegativity is a measure of an atom's ability to attract and hold onto electrons. When two atoms that form a bond have a significant difference in electronegativity, the atom with the higher electronegativity will attract the bond electrons more strongly, resulting in an unequal sharing of electrons. This unequal sharing creates a dipole, where one end of the bond becomes partially negative and the other end becomes partially positive, thereby increasing the bond's polarity.
In cases where the electronegativity difference is large enough, the bond approaches the characteristics of an ionic bond, where one atom completely transfers electrons to the other. However, the term "completely ionic" is reserved for bonds where the electronegativity difference is extremely high (typically greater than 2.0 on the Pauling scale), leading to full electron transfer rather than sharing.
This understanding clarifies the concept of polarity, emphasizing that as the difference in electronegativity grows, the bonds transition from being purely covalent (less polar) toward being more ionic (completely ionic) in nature, but they are considered more polar at varying levels of