<Tr> <Th> Nonpolar </Th> <Td> </Td> <Td> Diatomic molecules of the same element </Td> <Td> O </Td> <Td> Dioxygen </Td> </Tr> <Tr> <Td> </Td> <Td> Most carbon compounds </Td> <Td> CO </Td> <Td> Carbon dioxide </Td> </Tr> <P> Determining the point group is a useful way to predict polarity of a molecule . In general, a molecule will not possess dipole moment, if the individual bond dipole moments of the molecule cancel each other out . This is because dipole moments are euclidean vector quantities with magnitude and direction, and a two equal vectors who oppose each other will cancel out . </P> <P> Any molecule with a centre of inversion ("i") or a horizontal mirror plane ("σ") will not possess dipole moments . Likewise, a molecule with more than one C axis will not possess dipole moment because dipole moments cannot lie in more than one dimension . As a consequence of that constraint, all molecules with D symmetry (Schönflies notation) will, therefore, not have dipole moment because, by definition, D point groups have two or multiple C axis . </P>

Difference between a polar bond and a polar molecule