Question
The central atoms in CH4, NH3 and H2O are all said to have similar hybridisation but the bond angle H – A – H (where A is C, N or O) is different in each case. Explain stating in which case it is maximum and in which case it is minimum.
Solution
Due to sp3 hybridization, four such identical orbitals are symmetrically dispersed in space at an angle of 109°-28', which is the bond angle in methane. In NH3, there is one lone pair occupying one of the four symmetrical orbitals and due to its expansive nature suppresses the other three orbitals closer together at an angle of 107° and in H2O, there are two lone pairs as oxygen which suppresses the O – H bonds further closer together and they have an angle of 104.5°. Hence, H – A – H is maximum in CH4 and minimum in H2O.
