# Homework Help: Question regarding hybridization of Carbon

1. Sep 14, 2008

### aleferesco

The question that I have is regarding the hybridization of the Carbon atom in the molecule Carbanion

[CH3]-

My question is

Why is the carbon atom in Carbanion hybridized to sp3 orbitals instead of sp2?
shouldn't it be sp2 since the carbon atom is only making 3 bonds with hydrogen?

any help is truly appreciated

http://www.chem.uh.edu/Courses/Thummel/Chem3331/Notes/Chap4/Image178.gif [Broken]

Last edited by a moderator: May 3, 2017
2. Sep 14, 2008

### Gannon

The carbon is sp3 because it still has a lone pair of electrons to account for, which actually take up more space than a fourth bond would. Therefore, the geometry is still tetrahedral, with the lone pair located at the top. Like I said before, lone pairs take up more space; that's why in your first picture the hydrogens are a bit cramped together.

3. Sep 14, 2008

### aleferesco

ooo makes sense thanks

so does this mean that for everytime carbon is Hybridize do we have to account for the lone pair in order to determine if its is sp, sp2 or sp3???

4. Sep 14, 2008

### Gannon

You could think about it like this: to determine hybridization, count the number of electron domains and subtract 1, where a domain is either a bond (single, double, or triple) or a lone pair. For example, the methyl anion has 3 single bonds + 1 lone pair = 4 domains - 1 = 3 (sp3).

Another example is a double bonded oxygen (C=O). The oxygen has 1 double bond + 2 lone pairs = 3 domains - 1 = 2 (sp2).

Another example is a carbon in acetylene (or ethyne): H-C=C-H. Each carbon has 1 triple bond + 1 single bond = 2 domains - 1 = 1 (sp).

You can use this method for now, but in time you'll get good enough to identify the hybridization just by looking at the atom.

5. Nov 29, 2011

### tazr

Can cabon anion have s2p3 hybridization

6. Dec 21, 2011