Which type of bond involves unequal sharing of electrons?

A polar covalent bond involves unequal sharing of electrons between two atoms. This occurs when the atoms involved have different electronegativities, meaning one atom has a stronger ability to attract electrons than the other. As a result, the atom with higher electronegativity draws the shared electrons closer to itself, creating a partial negative charge, while the other atom acquires a partial positive charge. This unequal distribution of electron density leads to the formation of a dipole, where one end of the bond has a slight negative charge and the other has a slight positive charge.

In contrast, an ionic bond is characterized by the complete transfer of electrons from one atom to another, resulting in charged ions. A nonpolar covalent bond occurs when two atoms share electrons equally, usually between atoms of the same element or those with identical electronegativities. Metallic bonds involve the sharing of free electrons among a lattice of metal atoms, which also does not involve unequal sharing like polar covalent bonds. Hence, the polar covalent bond is distinctly recognized for its unequal sharing of electrons, leading to the properties associated with this type of bond.