Sigma Bonds vs Pi Bonds


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Tycho_Meimban_2B
Posts: 31
Joined: Wed Sep 21, 2016 2:57 pm

Sigma Bonds vs Pi Bonds

Postby Tycho_Meimban_2B » Wed Oct 26, 2016 11:01 pm

Which type of bond is stronger: Sigma Bonds or Pi Bonds? Also, how are triple bonds weaker than both double and single bonds?

Chem_Mod
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Re: Sigma Bonds vs Pi Bonds

Postby Chem_Mod » Thu Oct 27, 2016 12:48 pm

Triple bonds are stronger than double bonds, double bonds stronger than single bonds. Generally a pi bond is weaker than a sigma bond. A double bond is made up of a sigma bond and a pi bond. A triple bond is made up of two pi bonding interactions and a sigma bonding interaction.

Jonathan Sarquiz 3F
Posts: 32
Joined: Fri Jul 15, 2016 3:00 am

Re: Sigma Bonds vs Pi Bonds

Postby Jonathan Sarquiz 3F » Thu Oct 27, 2016 12:49 pm

In a sigma bond, the electrons are in orbitals between the nuclei of the bonding atoms (in the plane of electron density), where electron density is greatest. The end-to-end axial overlap of electrons attracts the nuclei to form a strong bond. In a pi bond, the p-orbitals overlap side-to-side above and below the nuclei (equatorial plane), so this attraction is more of a "sideways" pull as opposed to a direct line of pulling. Additionally, the election density is spread out over a greater area. Thus, sigma bonds are stronger than pi bonds.

Triple bonds are actually stronger than double and single bonds. In a single bond, you have one sigma bond. In a double bond you have one sigma and one pi bond (strength of sigma + pi > strength of sigma). In a triple bond you have one sigma and two pi bonds (strength of sigma + 2 pi > strength of sigma + pi). Therefore, triple bonds are stronger than a double bond which is stronger than a single bond.


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