The molecules $\mathrm{BF}_{3}$ and $\mathrm{NF}_{3}$ are both covalent compounds, but $\mathrm{BF}_{3}$ is…

The molecules $\mathrm{BF}_{3}$ and $\mathrm{NF}_{3}$ are both covalent compounds, but $\mathrm{BF}_{3}$ is non polar whereas $\mathrm{NF}_{3}$ is polar. The reason for this is
  1. atomic size of boron is larger than nitrogen
  2. Boron is metal while nitrogen is gas
  3. $\mathrm{B}-\mathrm{F}$ bonds are non-polar while $\mathrm{N}-\mathrm{F}$ bonds are polar
  4. $\mathrm{BF}_{3}$ is planar but $\mathrm{NF}_{3}$ is pyramidal

Solution

The shape of $\mathrm{BF}_{3}$ is trigonal planar


and $\mu=0$ hence it is non polar.
The shape of $\mathrm{NF}_{3}$ is pyramidal

and $\mu \neq 0$ hence it is polar. ~

Asked in: JEE-TOPICTESTS-CHEMISTRY

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