Molecular polarity: dipoles add as vectors
A molecule can contain polar bonds without being polar overall. Both bond polarity and three-dimensional geometry must be considered.
Understand before calculating
A molecule can contain polar bonds without being polar overall. Both bond polarity and three-dimensional geometry must be considered.
Example
In linear CO₂, the two C=O bond dipoles cancel by symmetry; in bent H₂O they do not.
The classic trap
Do not turn a model into a literal photograph of reality. Scientific models select particular properties to explain or predict a phenomenon; knowing their limits is part of using them correctly.
Understanding check
Explain the concept to someone who knows the periodic table but not this chapter. Then give one example and one situation where the most common shortcut would become misleading.
In linear CO₂, the two C=O bond dipoles cancel by symmetry; in bent H₂O they do not.