The Total solution for NCERT class 6-12
The HNH angle value is higherthan HPH, HAsH and HSbH angles. Why? [Hint: Can be explained on thebasis of sp3 hybridisation in NH3 andonly s−p bonding between hydrogen and other elements of thegroup].
Hydride NH3 PH3 AsH3 SbH3
H−M−H angle 107° 92° 91° 90°
The above trend in the H−M−H bondangle can be explained on the basis of the electronegativity of the centralatom. Since nitrogen is highly electronegative, there is high electron densityaround nitrogen. This causes greater repulsion between the electron pairsaround nitrogen, resulting in maximum bond angle. We know thatelectronegativity decreases on moving down a group. Consequently, the repulsiveinteractions between the electron pairs decrease, thereby decreasing the H−M−Hbond angle.