What term describes a molecule with an unequal distribution of charge?

A molecule with an unequal distribution of charge is referred to as a polar molecule. This occurs when there is a significant difference in electronegativity between the atoms that are covalently bonded. For instance, in a water molecule (H₂O), the oxygen atom is more electronegative than the hydrogen atoms, resulting in a partial negative charge near the oxygen and partial positive charges near the hydrogen atoms. This dipole moment leads to polarity in the molecule, which is crucial for various biological processes, including hydrogen bonding and solubility in biological systems.

In contrast, nonpolar molecules have an even distribution of charge due to either identical atoms (such as in diatomic gases) or symmetrical arrangements of atoms, which means that there is no significant difference in electronegativity. Ionic molecules, formed through the transfer of electrons and characterized by the attraction between positively and negatively charged ions, exhibit charge separation but are not considered polar in the same context as covalent bonding. Covalent molecules, which can be either polar or nonpolar depending on the distribution of charges, do not inherently imply an unequal charge distribution without additional specification. Thus, the term that best describes a molecule with an unequal distribution of charge is polar molecule.