Q10.10P - Chemistry: Molecular Nature Of Matter And Change

Question

Draw Lewis structures of all the important resonance forms of

(a)  ${\mathbf{HNO}}_3\left({\mathbf{HONO}}_2\right)$

(b)  ${{\mathbf{HAsO}}_4}^{2-}\left({{\mathbf{HOAsO}}_3}^{2-}\right)$

Step-by-Step Solution

Answer

The Resonance hybrid forms of 

${\mathbf{HNO}}_3\left({\mathbf{HONO}}_2\right)$ = Trigonal Planar

${{\mathbf{HAsO}}_4}^{2-}\left({{\mathbf{HOAsO}}_3}^{2-}\right)$ = Trigonal Planar

Lewis Structure

A Lewis structure can be defined as the basic structure of a molecule which used the valence electron of each atom involved. In Lewis’s structure, the least electronegative atom will be the central atom. 

Explanation

N belongs to group 15 having 5 electrons in the valence required to give or take 3 electrons to fulfil its octet, O belongs to group 16 having 6 electrons in the valence shell requires 2 electrons to fulfil the octet. In Lewis’s structure, the N-atom needs 3 electrons which will be provided by the 3 O-atom. The O-atom is more electronegative than N-atom and becomes a negative charge and positive charge respectively. There is the movement of an electron from one O-atom to another O-atom. There is a movement of negative charge over electronegative O-atom and there is a positive charge over N-atom fulfil its octet.

                             

Clarification

As belongs to the group 15 having 5 electrons in the valence requires give or take 3 electrons to fulfil its octet, O-atom belongs to group 16 having 6 electrons in the valence shell and requires 2 electrons to fulfil the octet. In Lewis’s structure, the As-atom needs 3 electrons which will be provided by the 4 O-atom. The O-atom is more electronegative than As-atom and becomes a negative charge and positive charge respectively. There is the movement of electrons from one O-atom to another O-atom. The As-atom is under N-family and acquires a positive charge and there is the movement of the negative electron over the electronegative O-atom.