textbook #2.45

[Christine Nguyen 3D]

Consider the bonding in H2C==CHCHO. I'm having trouble with part (c) of this problem where we have to identify the composition of the bonds and the hybridization of each lone pair. I didn't understand this part when Lavelle lectured on it.

[Olivia Smith 2E]

By composition do you mean pi and sigma bonds? In my understanding hybridization is that you count up all the areas of electron density and that relates to the hybridization of an atom. For example, in the case of the left most carbon the hybridization would be sp^2 because it has 3 groups. 1group=s, 2 group=sp, 3= sp^2, 4=sp^3, 5=sp^3d etc.
Lone pairs and bonding regions both count as separate groups.

[AnnaNovoselov1G]

Another thing to remember is that single bonds are sigma bonds, double bonds consist of 1 sigma and 1 pi bond, and triple bonds consist of 2 pi bonds and 1 sigma bond. To determine the hybridization, you would consider both the number of lone pairs and the number of bonded atoms.