What is a polar covalent bond characterized by?

A polar covalent bond is characterized by the unequal sharing of electrons between two atoms. This occurs when the atoms involved have differing electronegativities, which is the tendency of an atom to attract electrons. In such cases, the atom with higher electronegativity will attract the shared electrons more strongly, leading to a distribution of electron density that is not uniform. This results in a dipole moment where one end of the bond becomes slightly negative (due to the greater electron density) and the other slightly positive. This property is fundamental in explaining the behavior of many molecules and their interactions, particularly in polar solvents and biological systems.

The other options describe different types of bonding or interactions that do not accurately represent the nature of a polar covalent bond. For instance, equal sharing of electrons happens in nonpolar covalent bonds, complete transfer of electrons is characteristic of ionic bonds, and no sharing refers to interactions like metallic bonding or certain types of interactions that do not involve covalent electron sharing at all.