σ vs π bond tips thread


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Alexander Hari 1L
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Joined: Wed Feb 14, 2018 3:02 am

σ vs π bond tips thread

Postby Alexander Hari 1L » Sat Jun 02, 2018 3:50 pm

Thread on making tips on how to memorize σ vs π bonds
One way I remember the difference is the pi symbol has 2 "legs" extending from the symbol itself, and in lecture Dr. Lavelle gave the example of two markers connected and if you attempt to spin it on its axis, then the bond breaks.

JoeyAnn Mateo 1D
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Joined: Fri Apr 06, 2018 11:04 am

Re: σ vs π bond tips thread

Postby JoeyAnn Mateo 1D » Sat Jun 02, 2018 4:15 pm

Another alternative is that σ bonds can spin, and the circle shape of O resembles wheels.

Andre-1H
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Joined: Fri Apr 06, 2018 11:01 am

Re: σ vs π bond tips thread

Postby Andre-1H » Sat Jun 02, 2018 8:40 pm

What do we need to know about the properties of sigma and pi bonds? I remember in class it had something to do with rotation, and that would break the pi bond, why would the rotation then not affect the sigma bond?

Maria Roman 1A
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Re: σ vs π bond tips thread

Postby Maria Roman 1A » Sun Jun 03, 2018 12:33 am

Andre-1H wrote:What do we need to know about the properties of sigma and pi bonds? I remember in class it had something to do with rotation, and that would break the pi bond, why would the rotation then not affect the sigma bond?


Since a sigma bond consists of only 1 bond, it is able to rotate easily. However, pi bonds cannot rotate since they have two bonds holding the atoms together.

Vienna Cimetta 1L
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Joined: Thu Feb 01, 2018 3:01 am

Re: σ vs π bond tips thread

Postby Vienna Cimetta 1L » Sun Jun 03, 2018 4:49 pm

Generally double bonds are stronger than single bonds, and pi bonds are more likely to break than sigma bonds. Because pi bonds do not allow for rotation, they are often the first to break during a reaction. If you see a double bond in a molecule, just know one is a sigma bond and one is a pi bond. In a triple bond, one is a sigma bond and two are pi bonds (you can only have one sigma bonds).

Sarah Brecher 1I
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Joined: Fri Apr 06, 2018 11:02 am

Re: σ vs π bond tips thread

Postby Sarah Brecher 1I » Sun Jun 03, 2018 5:58 pm

It's also helpful to know that pi bonds will always be parallel p-orbitals overlapping and you can only have up to 2 pi bonds, which is why only up to triple bonds exist (1 sigma bond, 2 pi bonds).


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