Skip to content
CHEM 121 Studioby Learn4Less · UBC CHEM 121

CHEM 121 glossary

Polar molecule

A molecule with a net dipole moment, because its bond dipoles do not cancel. A molecule is nonpolar when it has no polar bonds, or when a symmetric shape with identical outer atoms cancels them.

Central C atom bonded to 2 H and 2 Cl atoms, with no lone pairs.ClHCHCl109.5°Ideal bond angle: 109.5°
CHX2ClX2\ce{CH2Cl2}: the two C–Cl dipoles are 109.5° apart and cannot cancel.

Example

OCS\ce{OCS} is linear like COX2\ce{CO2}, but its C=O and C=S dipoles are unequal, so OCS\ce{OCS} is polar while COX2\ce{CO2} is not.

See alsoDipole momentBond dipoleMolecular geometryDipole–dipole forces