sigma and pi bonds


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Angela Grant 1D
Posts: 67
Joined: Fri Sep 28, 2018 12:25 am

sigma and pi bonds

Postby Angela Grant 1D » Tue Nov 27, 2018 11:34 pm

what makes sigma bonds weaker than pi bonds?

Chloe Thorpe 1J
Posts: 77
Joined: Fri Sep 28, 2018 12:16 am

Re: sigma and pi bonds

Postby Chloe Thorpe 1J » Tue Nov 27, 2018 11:54 pm

I thought that pi bonds were weaker than sigma bonds since the amount of overlap in a sigma bond is greater than that in a pi bond. I try to imagine the lobes of the p-orbitals overlapping in a sigma bond versus a pi bond; the head-to-head overlay > side-to-side overlay.

Matthew Tran 1H
Posts: 165
Joined: Fri Sep 28, 2018 12:16 am

Re: sigma and pi bonds

Postby Matthew Tran 1H » Tue Nov 27, 2018 11:57 pm

Sigma bonds are actually stronger than pi bonds because there is more electron interaction (head-to-head orbital overlap vs. side-by-side overlap). You may be getting confused with single vs. double bonds. Single bonds are weaker than double bonds because there are less electrons involved (2 vs. 4). Also, double bonds have a pi bond in addition to a sigma bond while single bonds only have a sigma bond. Obviously the fact that there is one more bond means that the double bond is shorter and stronger.

Josceline 3J
Posts: 33
Joined: Fri Sep 28, 2018 12:21 am

Re: sigma and pi bonds

Postby Josceline 3J » Tue Nov 27, 2018 11:58 pm

I think it is the other way around. Pi bonds are weaker than the sigma bonds. Pi bonds are easier to break. I think it has to do with the sigma bonds been closer to the nucleus or something like that.

Nancy Hu - 4E
Posts: 30
Joined: Fri Sep 28, 2018 12:28 am

Re: sigma and pi bonds

Postby Nancy Hu - 4E » Tue Nov 27, 2018 11:59 pm

Pi bonds by themselves are actually weaker than sigma bonds because there is less area of overlap between p orbitals than s orbitals. Single bonds are weaker than double bonds because single bonds has only a sigma bond while double bonds have a sigma and pi bond.

Vanadium Wang 4H
Posts: 60
Joined: Fri Sep 28, 2018 12:19 am

Re: sigma and pi bonds

Postby Vanadium Wang 4H » Wed Nov 28, 2018 1:38 am

Pi bonds are usually weaker than sigma bonds. Quantum mechanics says this is because the orbital paths are parallel so there is much less overlap between the p-orbitals.


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