Water has two lone pair of electrons while methane has none-Justify *
Answers
Answer:
The difference in the bond angles of CH4, H2O and NH3 can be explained using VSEPR Theory ( Valence Shell Electron Pair Repulsion theory ).
According to VSEPR theory the rupulsive force between bond pairs and lone pairs are not same. But, repulsive force act as follows :
Bond pair - Bond pair < Bond pair-Lone pair < Lone pair -Lone pair .
So, due to varying repulsive force the bond pairs and lone pairs distorted from regular geometry and organize themselves in such a way that repulsion will be minimum and stability will be maximum.
So, in case of CH4 there are 4 bond pairs and no lone pair of electrons. So, it remains in its regular geometry i.e, tetrahedral with 109.5 ° .
In case of NH3 that are 3 bond pairs and single lone pair. Since, repulsion between bond pair and lone pair is more than that of 2 bond pairs so, bonds are slifhtly constricted and form pyramidal shape with bond angle 107° .
Similarly, H2O has 2 bond pairs and 2 lone pairs. So, according to VSEPR there is large repulsion between lp-lp. Again repulsion between lp-bp is more than that of 2 bond pairs. So, two bonds are more constricted to form V shape molecule with bond angle 104.5° .
I think the concept is pretty much clear now. For any further doubts, details or suggestions comments are heartily welcomed.