Master the Molecules: Ace Your 2026 Molecular & Cellular Biology Exam 1!

Polarity in a molecule comes from unequal sharing of electrons between atoms with different electronegativities, which creates partial charges on atoms. When those bond dipoles don’t cancel due to the molecule’s geometry, the molecule has a net dipole moment and is polar. The statement reflects this idea: there is a net dipole moment because electrons are shared unequally, giving one end of the molecule a partial negative charge and the other a partial positive charge. Water is a classic example: oxygen pulls more strongly than hydrogen, and the bent shape prevents cancellation, yielding a net dipole.

In contrast, a molecule with no net dipole moment is nonpolar, which would describe either nonpolar bonds or a symmetric arrangement that cancels dipoles. Ionic bonds involve full transfer of electrons to form ions, not a covalent molecule with a dipole moment.