Answer : The molecular geometry of [tex]NI_3[/tex] is trigonal pyramidal.
Explanation :
Formula used :
[tex]\text{Number of electron pair}=\frac{1}{2}[V+N-C+A][/tex]
where,
V = number of valence electrons present in central atom
N = number of monovalent atoms bonded to central atom
C = charge of cation
A = charge of anion
The given molecule is, [tex]NI_3[/tex]
[tex]\text{Number of electron pairs}=\frac{1}{2}\times [5+3]=4[/tex]
Number of bond pair = 3
Number of lone pair = 1
The total number of electron pair are 4 that means the hybridization will be [tex]sp^3[/tex] and the electronic geometry of the molecule will be tetrahedral.
But as there are 3 atoms around the central oxygen atom, the fourth position will be occupied by lone pair of electrons. The repulsion between lone and bond pair of electrons is more and hence the molecular geometry will be trigonal pyramidal.
Hence, the molecular geometry of [tex]NI_3[/tex] is trigonal pyramidal.
