1. The problem statement, all variables and given/known data Explain why the H-N-H bond angle in ammonia is less than that of H-C-H in methane. Though this is a worked example. I just want to understand the explanation given for the problem. 2. Relevant equations 3. The attempt at a solution As I said, this is a worked example, am just battling to understand the explanation given for the problem. Here is the explanation given for the problem: The electron cloud formed by the unshared pair in NH3 spread out over a greater volume than that of the three pairs connected to hydrogen atoms. This would tend to force the bonding pairs closer to one another and thereby reduce the bond angle to less than the bond angle in the tetrahedral methane. I don't want to memorise this explanation without understanding it. That is why I have decided to post the problem into the forum. Thank you!