Double Bond vs Single Bond Length

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Tracey Tran 3I
Posts: 50
Joined: Thu Jul 11, 2019 12:16 am

Double Bond vs Single Bond Length

Postby Tracey Tran 3I » Wed Oct 23, 2019 9:20 pm

Are double bonds shorter than single bonds because they're stronger? If so, then why is the observed N-O bond length in the NO3- 1.24 A.

VPatankar_2L
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Re: Double Bond vs Single Bond Length

Postby VPatankar_2L » Wed Oct 23, 2019 9:35 pm

The length of the bonds is in part based on the distance between two atoms. Atoms that form double bonds with one another have a stinger attraction between them which means they are pulled closer together than if they were connected by a single bond. Thus, the distance between them is smaller which means that double bonds are shorter than single bonds.

Montana James 4G
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Joined: Wed Sep 18, 2019 12:21 am

Re: Double Bond vs Single Bond Length

Postby Montana James 4G » Wed Oct 23, 2019 10:21 pm

to add on, I think Dr Lavelle said that in actual experimental data, all the bond lengths are the same (1.24A). So the Lewis structure is just a model.

Kishan Shah 2G
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Joined: Thu Jul 11, 2019 12:15 am

Re: Double Bond vs Single Bond Length

Postby Kishan Shah 2G » Wed Oct 23, 2019 10:32 pm

Correct, the lewis structure is just a rough model and Dr. Lavelle did say that the actual length is 1.24 angstrom. The double bonds and triple bonds contain more electrons, thereby exerting a stronger force on the nuclei of the atoms and this pulls the atoms closer together hence shorter bond lengths.

Arvind 4G
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Re: Double Bond vs Single Bond Length

Postby Arvind 4G » Thu Oct 24, 2019 12:20 am

In general, yes. The NO3 is a special case of resonance as its double bond is not on one of the bonds, but rather each bond is a bit stronger than a single bond and a bit weaker than a double bond.

TheresaDsilva4A
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Joined: Thu Jul 25, 2019 12:17 am

Re: Double Bond vs Single Bond Length

Postby TheresaDsilva4A » Thu Oct 24, 2019 10:18 am

I spoke with an LA after class about this specific topic. He explained that the electrons of the NO3- ion are evenly distributed amongst the three bonds. Thus, in reality, there is no distinguishable difference between the double/single bonds. This is the reasoning behind the experimental 1.24-angstrom value that Dr. Lavelle provided. I hope this add-on helps :)

Sarah Zhari 1D
Posts: 87
Joined: Sat Sep 14, 2019 12:16 am

Re: Double Bond vs Single Bond Length

Postby Sarah Zhari 1D » Thu Oct 24, 2019 10:26 am

Additionally, in resonance structures, the bond lengths are equal due to the delocalization of electrons between the atoms. The molecule, as a result, has a lower energy, and this helps to stabilize the molecule.


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