This is due to the symmetry in some polar molecules,so the dipoles cancel each other out.
For example, water is a polar molecule, however, as water is negatively charged on one side and positively charged on the other, the charges cancel each other out.
Isn't water a polar molecule? It has a 'bent' shape so the charges cannot cancel out.
CO2 is a good example, the C=O bond is polar, however the molecule is linear, so if you look at the central carbon, it has a delta - on either side of it, so they cancel eachother and the overall molecule has no permanent dipole. More complicated ones would be something like SF6, the S-F bond is polar but the octahedral shape is symmetrical about the central S atom, so there is no overall dipole.
CO2 is a good example, the C=O bond is polar, however the molecule is linear, so if you look at the central carbon, it has a delta - on either side of it, so they cancel eachother and the overall molecule has no permanent dipole. More complicated ones would be something like SF6, the S-F bond is polar but the octahedral shape is symmetrical about the central S atom, so there is no overall dipole.
thank you very much! at my school we didn't get taught any of the bonding topic!!