Question

Solve this:

14. Arrange the following species in increasing order of bond angle.
$$\begin{gathered} {\mathrm{NF}}_3,{\mathrm{NCl}}_3,{\mathrm{NBr}}_3,{\mathrm{Ni}}_3 \\ \left(1\right){\mathrm{NF}}_3<{\mathrm{NCl}}_3<{\mathrm{NBr}}_3<{\mathrm{Nl}}_3 \\ \left(2\right){\mathrm{NF}}_3<{\mathrm{NBr}}_3<{\mathrm{Nl}}_3<{\mathrm{NCl}}_3 \\ \left(3\right){{\mathrm{Nl}}_3}_3<{\mathrm{NBr}}_3<{\mathrm{NCl}}_3<{\mathrm{NF}}_3 \\ \left(4\right){\mathrm{NBr}}_3<{\mathrm{Nl}}_3<{\mathrm{NF}}_3<{\mathrm{NCl}}_3 \end{gathered}$$

Answer 1

The NF₃ is stable, NCl₃ is unstable while NBr₃ and NI₃ are unknown.

Since central atom is N in all cases, then bond angle increases with decreases in electronegativity of surrounding atoms. It happens in those molecules which have bent or pyramidal structure. Here, all the given N-halides are pyramidal in shape.

Since order of electronegativity is F > Cl > Br > I
Hence, increasing order of bond angle is NF₃ < NCl₃< NBr₃ < NI₃