Bonds

(Polar molecules, Non-polar molecules, etc.)

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Courtney McHargue 1I
Posts: 56
Joined: Fri Sep 28, 2018 12:17 am

Bonds

Postby Courtney McHargue 1I » Sun Nov 25, 2018 11:39 am

Do single, double and triple bonds always have to be made from the exact number of sigma and pi bonds each time, or can they be made with other ratios of the two?

A De Castro 14B 2H
Posts: 75
Joined: Fri Sep 28, 2018 12:29 am

Re: Bonds

Postby A De Castro 14B 2H » Sun Nov 25, 2018 11:57 am

A single bond is always a sigma bond.
A double bond is always one sigma bond and one pi bond.
A triple bond is always one sigma bond and two pi bonds.

David S
Posts: 54
Joined: Fri Sep 28, 2018 12:15 am

Re: Bonds

Postby David S » Sun Nov 25, 2018 12:05 pm

By ratios, I'll take it that you mean a particular orbital in question doesn't strictly exist between two directly bonded atoms.

You can definitely have delocalized π orbitals that spread over entire portions of molecules, and not belonging wholly between two directly bonded atoms. You will have whole number of sigma bonds though because sigma bonds don't really get delocalized.

On that note, I don't think we need to use actual numbers to describe the bonds between two atoms in situations involving delocalized orbitals. For example, with benzene, we are not expected to say that there is 1 sigma + 3π /6 bonds → 1 sigma + 0.5 π orbitals for each C--C bond, and this basic calculation is probably inaccurate anyways.


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