What is a polar covalent bond?

A polar covalent bond is characterized by the unequal sharing of electrons between two atoms. This occurs when the two atoms involved have different electronegativities, meaning one atom has a stronger tendency to attract electrons than the other. As a result, the atom with the higher electronegativity attracts the shared electrons more strongly, leading to an uneven distribution of electron density. This creates a dipole, where one end of the bond becomes slightly negative (the more electronegative atom) and the other end becomes slightly positive (the less electronegative atom).

In contrast, a bond where electrons are shared equally would be classified as a nonpolar covalent bond, as there would be no significant charge separation. Bonds that involve only ionic interactions do not involve the sharing of electrons at all, instead, they involve the complete transfer of electrons from one atom to another, creating ions. Lastly, a bond formed from metallic elements typically represents metallic bonding, which involves the sharing of free electrons among a lattice of positive metal ions, rather than a specific polar or nonpolar scenario. Thus, the definition of a polar covalent bond aligns precisely with the scenario of unequal sharing, confirming that the correct choice is the one that describes this property accurately.