Question

In which cases do you expect deviations from the idealized bond angle? PF3 SBr2 CS2 CHCl3

Answer 1

Answer: CHCl3 and SBr2 and PF3

CHCl3 - should have a bond angle of 109.5 as it is tetrahedral but the bond angle between the CH bond and CCl bonds will be less than 109.5 and the angle between CCl bonds will be more than 109.5. This is because the Cl atoms have electrons around them while the H does not so the Cl atoms repel each other and widen the bond angle. 

CS2 will have  180 which is what is expected because there are no lone pairs on the C just like CO2. 

SBr2 should be 104.5 just like in H2O but because the Br atoms have electrons around them they will repel each other more than the H atoms in H2O so the bond angle will be more than 104.5 

PF3 should be 107 just like NH3 but the F atoms have electrons around them they will repel each other more than the H atoms in NH3 so the bond angle will be more than 107.

Answer 2

CHCl3 because there are more than two atoms in this molecule that are different. Hydrogen has a small electron cloud and occupies less space, where Cl has a larger electron cloud and occupies more space, this would make it different than the expected tetrahedron shape.