Resonance Structures

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Lilyana Villa 1J
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Joined: Sat Aug 17, 2019 12:15 am

Resonance Structures

Postby Lilyana Villa 1J » Sun Oct 27, 2019 10:32 pm

Can someone give me an explanation on why we have to create resonance structures for some molecules instead of just a single lewis structure?

Andrew Pfeiffer 2E
Posts: 101
Joined: Sat Sep 28, 2019 12:16 am

Re: Resonance Structures

Postby Andrew Pfeiffer 2E » Sun Oct 27, 2019 10:36 pm

Resonance structures are necessary when you can draw the same arrangement of atoms with different arrangements of e-. This occurs on account of the number of double bonds and lone pairs on each atom (you can find the best arrangement using formal charge, which we learned about last lecture).
Last edited by Andrew Pfeiffer 2E on Sun Oct 27, 2019 10:40 pm, edited 1 time in total.

Eesha Chattopadhyay 2K
Posts: 104
Joined: Fri Aug 09, 2019 12:16 am

Re: Resonance Structures

Postby Eesha Chattopadhyay 2K » Sun Oct 27, 2019 10:39 pm

Resonance structures are necessary because the e- is not just occupying that one formation. The electrons are actually in a position that is an average of the possible structures so saying that one is correct is not true. We draw all of them because it shows that there is more than one possibility of how the electrons can be arranged.

Posts: 105
Joined: Sat Aug 17, 2019 12:16 am

Re: Resonance Structures

Postby Mulin_Li_2J » Sun Oct 27, 2019 10:47 pm

From what I understand of resonance, those alternative structures Dr. Lavelle shew us in his lecture are contributing resonance structures of the molecule because all of these structures are plausible states of the molecule but with different formal charges and electron distributions. However, experimental data shows that the real structure of the molecule is a combination of all its contributing resonance structures due to de-localization of electrons in the molecule. For example, NO3- has two single bonds and one double bond. It has three contributing resonance structures as a single nitrogen atom can have double bond with any of the three oxygen atoms. Since none of the three structures is a true representation of the molecule, the real structure of NO3- is a combination of all three structures, and the nitrogen atom forms three identical bonds with three oxygen atoms with bond length between a double bond and a single bond. Hope this can help!

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