What characterizes a polar molecule?

A polar molecule is characterized by a covalent bond with unequal sharing of electrons. This unequal sharing occurs due to differences in electronegativity between the atoms involved in the bond. In a polar covalent bond, one atom exerts a stronger pull on the shared electrons because it has a higher electronegativity, leading to the development of partial positive and partial negative charges within the molecule. This creates a dipole, which is a key feature of polar molecules, resulting in their unique physical properties, such as higher boiling and melting points compared to nonpolar molecules.

In contrast, a covalent bond with equal sharing of electrons leads to nonpolar molecules, while the presence of ionic bonds creates ionic compounds, which are not classified as polar molecules. Lastly, molecules without partial charges characteristically do not have polar characteristics, as they lack the essential separation of electrical charge that defines a polar molecule. Thus, the definition of polar molecules hinges on the unequal sharing of electrons within covalent bonds.