Delocalized Pi bond

[705676154]

How do I know if a species contains a delocalized pi bond?

[Lucas Koch 1I]

A species contains a delocalized pi bond when it has resonance. Remember that double and triple bonds contain pi bonds and species with resonance have delocalized bonds due to actual structures being an average of possible structures. This means that any double or triple bond in a resonance structure can be swapped for another position and is therefore delocalized and because it has a pi bond, the pi bond is the one delocalized.
If it has resonance, it has a delocalized pi bond.

[Sneha Anantharaman2D]

When a species has resonance, it will have a delocalized pi bond. This is because when a specific structure has resonance, it will not have double bonds stable between two specific atoms and will rather have the bonds be an average of the different bonds present within a molecule. As a result, the pi bonds are not limited to a single bond, but will be delocalized along the entire structure.

[Simone Byun 1F]

Any time a molecule has resonance, the pi bond will be delocalized. This is because the pi bond is not limited to one bond, but will be averaged out over all of the resonance structures.

[Wilson Zheng 1L]

When there is resonance (single bond with at least one double bond or more), you can assume that delocalized pi bonds will exist!