I came across a problem : ClO2 molecule, what is the hybridization of the central atom. Here is what I did :

I came across a problem : ClO2 molecule, what is the hybridization of the central atom.

Here is what I did :

1) Central atom is chlorine since least electronegative

2) Counted total valence electrons : 7 + 2*6 = 19 e-

3) Draw skeleton lewis structure : 19-4 = 15e- left

4) Fill in octets for terminal atoms (oxygens), 15-12 = 3e- left

5) I am left with a lone pair and a single unpaired electron on the chlorine

6) Add two double bonds to chlorine atom, properly filling octet, chlorine is on third period so can have expanded octet (total 9e- including single unpaired e-)

here is my problem : chlorine has two atoms bonded to it, and one lone pair, it's steric number is 2+1 = 3. Therefore it's hybridization should be sp2.

However the answer in the problem set says it is sp3.

Does the single unpair electron count as a lone pair and get hybridized?