1.the bond angle in Nf3 is 130° whereas in BF3 is 120° . what factor account for this difference in bond angle?
Answers
Answer:
In BF3 molecule boron has 3 valency electrons and all are shared with F atoms. Also it has 3 hybrid orbitals, as it is required to form three bonds with 3F atoms. Now 3 orbitals can be arranged in 120° with each other for maximum stability of the molecule.
On the other hand in NF3 nitrogen has 5 valency electrons, but 3 of them are shared with 3F atoms. And there are remaining two electrons or you can say a lone pair. Now N has four hybrid orbitals ,as 3 of them are occupied by electrons forming bond with F atoms and one more orbital is occupied by the two remaining electrons.Now these 4 hybrid orbitals can be arranged in 109°28' . But due to the electrons repulsion of the lone pair electrons with bonded electrons, the molecule stabilize itself when there is 102°5' . between each bond.