Molecular polarity and choosing intermolecular forces
≈ 48 minMolecular polarity and choosing intermolecular forces
Bond polarity arises from unequal sharing of electrons between atoms with different electronegativities. Molecular polarity depends on both the bond polarities and the three-dimensional shape: polar bonds can cancel in a symmetrical molecule. Carbon dioxide has polar C=O bonds but is linear, so the bond dipoles cancel; water is bent, so its O-H bond dipoles do not cancel. Once molecular polarity is established, select the relevant intermolecular forces. All molecules have London forces; polar molecules also have dipole-dipole attractions; molecules with H bonded to N, O or F can form hydrogen bonds.
Work it through
Compare CO₂ and H₂O. Both contain oxygen and have polar bonds, but CO₂ is linear and non-polar overall. H₂O is bent and polar, and its O-H groups permit hydrogen bonding. The correct explanation has two linked parts: shape determines net polarity, and polarity helps determine the forces between molecules.
Mastery target
Use bond polarity and molecular shape together to decide whether a molecule is polar and predict its strongest relevant intermolecular attraction.
Why is CO₂ non-polar overall?
Name the key chemistry term from Molecular polarity and choosing intermolecular forces that best fits the explanation and visual model.
Which molecule can form hydrogen bonds between its molecules?
Which statement corrects a common misunderstanding in Molecular polarity and choosing intermolecular forces?