Why is the bond angle between Cl and Cl in trichloromethane more than 109.5degree ?
Is it because the repulsion of bonding pair between C-H and C-Cl weaker (I assume that the distance between both bonding pair is longer and hence the repulsion is weaker resulting in lower angle which in turns increase the bond angle between C-Cl and C-Cl) and hence increasing the angle between C-Cl and C-Cl.
It is a polar molecule, so the bonding pairs repulsion are stronger between C-Cl and C-Cl and weaker between C-H and C-Cl ( As the distance between the bonding pair is longer due to the fact that Cl which is very electronegative attracts the bonding electrons closer , making the distance longer from the bonding pair in C-H), bear in mind that in tetrahedron, when the C-H and C-Cl angle decreases, the C-Cl and C-Cl's angle will increase.
Another idea is that electrons are very dense in the C-Cl areas(Delta - area), and hence their repulsion are greater than expected and so is the angle.
I don't know if my thinking is right but I would like you to clarify me, thanks in advanced.