Energy and Stability in Delocalization

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Lorraine Medina 3E
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Energy and Stability in Delocalization

Postby Lorraine Medina 3E » Mon Nov 02, 2020 3:30 pm

Hi! Can anyone explain why delocalization of electrons lowers energy but also increases stability? Dr. Lavelle said it in his lecture for today (11/2), but I failed to understand why this occurs. Thanks for the help!

DanielHong2L
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Re: Energy and Stability in Delocalization

Postby DanielHong2L » Mon Nov 02, 2020 3:34 pm

Lorraine Medina 3C wrote:Hi! Can anyone explain why delocalization of electrons lowers energy but also increases stability? Dr. Lavelle said it in his lecture for today (11/2), but I failed to understand why this occurs. Thanks for the help!


Delocalization of the electrons increases the size of the molecule which makes it more stable
In the Heisenberg lesson, there was an example of how limiting the electrons to a really small space would be unstable, and even smaller would be physically impossible so a larger space would increase stability.
I'm not sure about the lowering of energy due to delocalization, it might have to do with the amount of bonds(?)

Personally that is the extent I understand this topic, sorry! I hope this helps a little bit!

Ria Nawathe 1C
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Re: Energy and Stability in Delocalization

Postby Ria Nawathe 1C » Mon Nov 02, 2020 3:41 pm

Here is the textbook's explanation for why it increases stability (it's in Focus 2B):

"As well as delocalizing electrons over the atoms, resonance also lowers the energy below that of any single contributing structure and helps to stabilize the molecule. This lowering of energy occurs for quantum mechanical reasons. Broadly speaking, the wavefunction that describes the resonance structure is a more accurate description of the electronic structure of the molecule than the wavefunction for any single structure alone, and the more accurate the wavefunction, the lower the corresponding energy."

DanielHong2L
Posts: 55
Joined: Wed Sep 30, 2020 9:51 pm

Re: Energy and Stability in Delocalization

Postby DanielHong2L » Mon Nov 02, 2020 4:01 pm

DanielHong2L wrote:
Lorraine Medina 3C wrote:Hi! Can anyone explain why delocalization of electrons lowers energy but also increases stability? Dr. Lavelle said it in his lecture for today (11/2), but I failed to understand why this occurs. Thanks for the help!


Delocalization of the electrons increases the size of the molecule which makes it more stable
In the Heisenberg lesson, there was an example of how limiting the electrons to a really small space would be unstable, and even smaller would be physically impossible so a larger space would increase stability.
I'm not sure about the lowering of energy due to delocalization, it might have to do with the amount of bonds(?)

Personally that is the extent I understand this topic, sorry! I hope this helps a little bit!


Just asked Dr. Lavelle on why there is less energy in delocalization and simply put

Generally, as the charge is delocalized over a larger area, it lowers the energy of the system, so thus it increases energy.

A more complicated answer is as follows (to the best of my understanding)
As different energies are modeled in a particle in a box system with n=1,2,3,4 etc, the energy increases
In a similar manner,
within the particle in a box model, you could increase the volume, and the calculations result that the energy decreases within a larger volume / area.

Hope this helps a lil bit more :)


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