Strength of sigma and pi bonds


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Shanzey
Posts: 120
Joined: Wed Sep 18, 2019 12:20 am

Strength of sigma and pi bonds

Postby Shanzey » Sun Nov 24, 2019 12:40 am

In one of the UA sessions, the UA mentioned that sigma bonds require more energy to break than pi bonds. Why is that?

pauline young 1L
Posts: 50
Joined: Thu Jul 11, 2019 12:15 am

Re: Strength of sigma and pi bonds

Postby pauline young 1L » Sun Nov 24, 2019 12:42 am

there are more electron overlaps in sigma bonds which make them a lot stronger than pi bonds and thus requiring more energy to break

Haley Pham 4I
Posts: 51
Joined: Fri Aug 09, 2019 12:16 am

Re: Strength of sigma and pi bonds

Postby Haley Pham 4I » Sun Nov 24, 2019 3:21 am

The electrons in a sigma bond are directly between the nuclei of the atoms are as close to the nuclei as possible, so the nuclei strongly hold onto the electrons, making it difficult to break the bond. The electrons in a pi bond are further away from the nuclei, so the nuclei weakly attract the electrons, making it less difficult to break the bond.

AmyL_3L
Posts: 50
Joined: Fri Aug 09, 2019 12:17 am

Re: Strength of sigma and pi bonds

Postby AmyL_3L » Sun Nov 24, 2019 10:59 am

Sigma bonds are harder to break due to the location of the electrons, which are very close to the nuclei.

Lauren Stack 1C
Posts: 100
Joined: Sat Aug 17, 2019 12:18 am

Re: Strength of sigma and pi bonds

Postby Lauren Stack 1C » Sun Nov 24, 2019 12:14 pm

If you think about the various diagrams we were shown of the orbital hybridization, you can see that the sigma bonds’ orbitals overlap much more than the orbitals of the pi bonds as they directly overlay each other.
This diagram I found helped me understand:
Image

005162902
Posts: 102
Joined: Wed Sep 18, 2019 12:15 am

Re: Strength of sigma and pi bonds

Postby 005162902 » Sun Nov 24, 2019 1:00 pm

The electrons overlap much closer to the nuclei in sigma bonds. This creates a greater pull on them because of the attraction between the positive nucleus and negative electrons. This strong attraction makes them harder to break than pi bonds, that have less electron overlap.

Omar Selim 1D
Posts: 108
Joined: Sat Jul 20, 2019 12:16 am

Re: Strength of sigma and pi bonds

Postby Omar Selim 1D » Sun Nov 24, 2019 1:03 pm

sigma bonds are harder to break than pi bonds because the former are a result of end-to-end bonding while the latter consist of side-to-side bonds

Anish Patel 4B
Posts: 59
Joined: Thu Jul 11, 2019 12:17 am

Re: Strength of sigma and pi bonds

Postby Anish Patel 4B » Sun Nov 24, 2019 1:08 pm

Since pi bonds represent parts of double and triple bonds (which are considered stronger than single bonds), why aren't pi bonds stronger?

Mariah
Posts: 104
Joined: Fri Aug 02, 2019 12:16 am

Re: Strength of sigma and pi bonds

Postby Mariah » Sun Nov 24, 2019 1:21 pm

Omar Selim 3H wrote:sigma bonds are harder to break than pi bonds because the former are a result of end-to-end bonding while the latter consist of side-to-side bonds


So then why are double bonds stronger than single bonds? If they contain a sigma and pi versus just one sigma?


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