pBlock ElementsII 1 Question 60
55. Statement I Although $\mathrm{PF} _{5}, \mathrm{PCl} _{5}$ and $\mathrm{PBr} _{5}$ are known, the pentahalides of nitrogen have not been observed.
Statement II Phosphorus has lower electronegativity than nitrogen.
(1994, 2M)
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Solution:
- Both Statement I and Statement II are independently correct but reason is not the correct explanation of Statement I. Nitrogen does not has any vacant $d$-orbitals, it cannot expand its valence shell beyond eight electrons, i.e. it cannot violate octet. Therefore, nitrogen forms only trihalides ( $\mathrm{N} X _{3}$ with eight electrons in valence shell of $\mathrm{N}$ ).
Phosphorus has vacant $3 d$-orbitals, it can expand its valence shell beyond eight electrons, its both trihalides and pentahalides exist.
