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### Focus Question 2.45

Posted: Mon Nov 26, 2018 11:37 am
Consider the bonding in H2C--CHCHO. Identify the composition of the bonds and the hybridization of each lone pair.

How would you determine the hybridization of a lone pair? Also why is the formal hybridization of the pi bond between the double bonded carbon atoms pi(C2p,C2p)?

### Re: Focus Question 2.45  [ENDORSED]

Posted: Mon Nov 26, 2018 3:10 pm
Lone pairs should usually be in hybridized orbitals for a lot of basic elements (N, O, halogens, etc.). For example, oxygen in this case should be $sp^{2}$ hybridized. It uses one of these hybridized orbitals to make a sigma bond with carbon, and it uses last p orbital to make the pi bond. The remaining two $sp^{2}$ orbitals hold the lone pair electrons. Pi bonds are usually not made with hybridized orbitals, which is why the formal bond description is pi (C2p, C2p), as it is using the two p orbitals on the carbon to form a pi bond.