Number of Molecular Orbitals

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YuniLee_1K
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Joined: Wed Sep 21, 2016 2:59 pm

Number of Molecular Orbitals

Postby YuniLee_1K » Mon Nov 07, 2016 2:52 am

I understand how to determine the actual number of molecular orbitals for a molecule, but I think I'm still a little confused on assigning molecular orbitals (in terms of sigma* or pi2s, etc). How do we determine this?

Caitlin Dillon 3G
Posts: 26
Joined: Wed Sep 21, 2016 2:56 pm

Re: Number of Molecular Orbitals

Postby Caitlin Dillon 3G » Mon Nov 07, 2016 7:18 am

The key is to not over think it! In a single bond, there is one sigma bond. In a double bond, there is one sigma and one pi bond. In a triple bond, there is one sigma and two pi bonds.

Caitlin Dillon 3G
Posts: 26
Joined: Wed Sep 21, 2016 2:56 pm

Re: Number of Molecular Orbitals

Postby Caitlin Dillon 3G » Mon Nov 07, 2016 7:30 am

Then, after determining whether you're looking at a pi bond or a sigma bond, you assign the hybridization orbital in order to go along with it. For example, if you were looking at the CH(subscript 2)(double bond)CHCHO,

The first C would have three regions of electron densities, thus the hybridization orbital would be 2sp^2. The single bond that it shares with the 2 H's can be represented as sigma(H1s,C2sp^2) and the double bond that it shares with the C next to it can be sigma(C2sp^2, C2sp^2) and pi(C2p, C2p).


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