Question

The ${H_3}P{O_3}$ can be represented by structures 1 and 2 shown above. Can these two structures be taken as the canonical forms of the resonance hybrid representing ${H_3}P{O_3}$? If not, give reasons for the same.

Answer 1

Hint: The canonical structure is the term also used for resonance structure where the bonding of the molecule is represented by different lewis structures where the transfer of charge takes place.

Complete answer:
Resonance structure is explained as the two or more lewis structures which collectively explain the electronic bonding of a single species. The resonance structure also explains the delocalized electrons which cannot be explained in a single lewis structure.
In many cases it is observed that a single lewis structure is not able to explain the bonding in a molecule as they possess partial charges and fractional bonds. Therefore, the resonance structure is used to describe the bonding.
Thus, the resonance is described as the merging of many contributing lewis structures which helps to describe the manner of bonding in the molecules. The resonance structure is also known as canonical structure.
In the given structures, it can be seen that the position of the atom is different in both the structure.
In the canonical form of the structure of ${H_3}P{O_3}$, the position of the atom remains the same only charge transfer from one atom to other atoms takes place.
Therefore, these two structures are not taken as the canonical forms of the resonance hybrid representing ${H_3}P{O_3}$.

Note:
In ${H_3}P{O_3}$, the phosphorus atom is bonded with one oxygen atom which is a double bond, one hydrogen atom by a single bond and two OH bonds by a single bond.