# How to Choose Orbitals for Hybridization

Recently, I was reviewing my textbook regarding orbital hybridization, and one of the problems was to determine the hybridization of each of the atoms in $$\text{CO}_2$$. I understand why the hybridization on the C atom is $$\text{sp}$$ and the hybridization on each of the O atoms is $$\text{sp}^2$$, but what I don't understand is how to determine which of the three p orbitals becomes hybridized.

This becomes especially relevant with the O atom, since in its normal state one of its p orbitals is full (2 electrons) while the other two p orbitals only have 1 electron each (meaning that the 3 p orbitals aren't interchangable). How do I know which of these 3 p orbitals become hybridized into $$\text{sp}^2$$ orbitals and which orbital stays as a regular p orbital?

Thanks for the help.

• The O atoms are probably sp, not sp2. And the three p-orbitals are perfectly interchangeable; nobody said you have to put the paired electrons in one particular p-orbital, after all. – orthocresol Mar 28 at 19:05
• There is no choosing. You hybridize the orbitals, and then put the electrons there. – Ivan Neretin Mar 28 at 19:06
• @IvanNeretin So do you fill the hybridized orbitals before the regular p orbitals, or vice versa? – Michael Mar 28 at 19:14
• Wait a bit more: you make bonding and antibonding molecular orbitals out of those hybridized atomic orbitals, and only then... – Ivan Neretin Mar 28 at 19:24
• @orthocresol In this case, how would I determine the electron configuration for something like this oxygen, knowing that it is sp2 hybridized and that I have 6 electrons to fill everything with (also I think it is sp2 because according to the lewis structure there are 2 nonbonding electron pairs and each o atom is double bonded to the c atom)? Thanks – Michael Mar 30 at 22:07