However, the polarity of bonded atoms is not the only factor in determining the overall polarity of a molecule, and by extension, intermolecular force. Molecular geometry as predicted by VSEPR is also important.
For example, if the various dipole moments within a molecule are oppositely directed in space, even though the particular bonds are polar, the molecule may have no net dipole moment at all, in which case the degree of intermolecular force is weak. Carbon dioxide is the quintessential example, a linear molecule in which the dipole moments of the carbon-oxygen bonds are oppositely directed.
From a test-writer's perspective, this kind of exception makes a good multiple choice question. Keep VSEPR in mind on the MCAT if you are faced with interpreting the overall polarity of a molecule. Don't forget to ask yourself whether the dipole moments of individual bonds cancel each other out.
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