Final answer:
A molecule with polar bonds can be nonpolar if it has a symmetric geometry causing the polarities to cancel out. Examples include CO₂ with a linear shape and BF3 with a trigonal planar shape.
Step-by-step explanation:
A molecule that contains polar bonds can be nonpolar if it has a symmetrical arrangement where the bond moments cancel each other out. This occurrence is due to the molecular geometry and symmetry of the molecule.
For instance, carbon dioxide (CO₂) is a molecule with two polar C=O bonds; however, due to its linear geometric shape, the dipoles of these polar bonds point in opposite directions and cancel out, therefore CO₂ is nonpolar.
Similarly, a molecule like boron trifluoride (BF3), despite having polar B-F bonds, is nonpolar because it has a trigonal planar shape which distributes the bond polarity evenly around the molecule.
Conversely, water (H₂O) with its bent shape and polar O-H bonds does not have symmetrical bond polarities, making it a polar molecule.
It's essential to apply VSEPR theory and Lewis structure knowledge to predict the three-dimensional geometry of the molecule which greatly influences its overall polarity.
Symmetry is key for a molecule to exhibit nonpolar characteristics despite containing polar bonds. If the polar bonds in a symmetric molecule are arranged in a geometry that allows their polarity vectors to cancel each other out, the molecule as a whole will be nonpolar.