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In class, Professor Lavelle talked about how resonance causes a delocalization of electrons. Can someone please elaborate on that for me? From what I can understand, it's because the molecular can have different bonds between the atoms which causes a delocalization of the electrons around the central atom; meaning that the electrons are not just shared between the two atoms, but all the atoms around the central atom. Am I on the right track?
I do think you are on the right track. A resonance hybrid is a sort of compromise between multiple versions of a molecule's electron configuration, a mixture of different resonance patterns. Molecules won't exist in these separate forms, or switch between them, but rather they will spread their electrons across multiple bonds to create stability/symmetry. This results in the concept of delocalized electrons. A subset of the molecular orbital theory, delocalization asserts that electrons exist in orbitals spread over the entire molecule. Spreading electron densities increases the stability of the molecule while creating charge distributions, signifying the importance of delocalization.
I have a further question. Specifically which electrons are delocalized when an atom exhibits resonance? For example in benzene there are technically 3 double bonds, but the molecule exhibits resonance, so instead there's an electron cloud full of delocalized electrons rather than 3 double bonds. I'm wondering which electrons would be in that electron cloud. For benzene would it just be the 6 electrons that would've been in the double bonds had the bonds exist? Or is it all of the electrons involved in bonding the carbon atoms together?
Cameron, only the six electrons involved in the electron cloud are considered delocalized electrons. By definition, a delocalized electron is one that does not have a specific location. Recall that this means that, in essence (but not actually...this is for conceptual visual purposes), there are bonds of length 1.5 instead of alternations between 1 and 2. The other six electrons between Carbon and Hydrogen are in no way affected by the delocalization. Hope that clears up your doubts.
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