Delocalized Pi Bond

(Polar molecules, Non-polar molecules, etc.)

Seraphina Joseph 1C
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Joined: Wed Sep 30, 2020 9:31 pm

Delocalized Pi Bond

What makes a Pi bond delocalized and how do you determine if a pi bond is regular or delocalized?

Isabelle Hales 1J
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Re: Delocalized Pi Bond

A delocalized pi bond occurs in molecules that have resonance structures. When the double bond can occur in more than one place, the atoms bind in such a way that they share electrons, causing the bonds to be in between single and double. When this occurs, the pi bond is delocalized because it is not in one specific place. For example, in Benzene (C6H6), the 6 carbons in the middle ring have 3 double bonds spread out with amongst them. However, because Benzene has resonance structures, the electrons will be shared between all 6 carbons, leading to 3 delocalized pi bonds.

Anh Trinh 1J
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Re: Delocalized Pi Bond

A delocalized pi bond is only present in molecules with resonance structures. For example, $O_{3}$ have resonance structures. There is a single bond and a double bond in $O_{3}$, but the double bond can be on either of the O atoms, so the molecule has two resonance structures. This means that this molecule has a delocalized pi bond because the pi orbitals extend over more than two atoms.

Seraphina Joseph 1C
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Joined: Wed Sep 30, 2020 9:31 pm

Re: Delocalized Pi Bond

I get it now! thank you so much

Posts: 95
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Re: Delocalized Pi Bond

This post was so helpful, I had a similar question. Thank you to all that responded!

Simi Kapila_3E
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Re: Delocalized Pi Bond

Delocalized pi bonds occur when a structure has resonance. They are considered delocalized because they do not have a single permanent location, due to the fact that the actual molecule is usually a mix of the resonance structures.

Lilly Catarozoli 1B
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Re: Delocalized Pi Bond

I think delocalized correlates to if the structure has resonance or not. If it has resonance, then the electrons would be delocalized because they don't have one singular place.

Mackenzie Stockton 2H
Posts: 97
Joined: Wed Sep 30, 2020 10:11 pm

Re: Delocalized Pi Bond

delocalized pi bonds occur when the molecule with the pi bond has resonance. Remember that resonance structures have atoms that all have the same bond lengths. For a resonance structure with double and single bonds, the actual bond length is in between double and single. Because all bond lengths have some double bond character, all bonds are delocalized pi bonds, in which the electrons are not localized/confined to a specific region of the molecule and are therefore free to move around.