How to find out the geometry of nitrate ion

Structure of molecule depends on its hybridization and lone pares of central atom.

• Hybridization of any molecule can be determined by the following formula:

H=1/2{ V + X - C + A}

V=no. of valence electrons in central atom

X=no. of monovalent atoms around the central atom

C= +ve charge on cation

A= -ve charge on anion

If H= 2, it means hybridization is sp.

If H= 3, it means hybridization is sp².

If H= 4, it means hybridization is sp³.

Now the given molecule is NO₃^-.

Here central atom is N.

V= 5

X= 0

C= 0

A= 1

H=1/2{5 + 0 - 0 + 1) = 3

So hybridization of N in NO₃^- is sp².

•  There is no lone pair on the N atom.

Hence there are 3 sp² hybridized molecular orbitals present at 3 corners of a triangle to give the molecule triangular geometry.