# In terms of structure and/or distribution of charge, why is CO_2 a nonpolar molecule?

Polarity reults from the geometric sum of the individual bond dipoles. For the ""^(delta^+)C=O^(delta^-) bond there is some polarity, some charge separation. However, this polarity is precisely balanced by geometric summation with the other ""^(delta^-)O=C^(delta^+) dipole, on the other side of the molecule. And thus carbon dioxide is a non-polar molecule.
On the other hand, for the carbon monoxide molecule, ""^(-)C-=O^+, there is necessairly some degree of molecular polarity.