Question

Why is $Pb{{O}_{2}}$ not peroxide?

Answer 1

Peroxide ion has the molecular formula ${{O}_{2}}^{2-}$. The treatment of metallic oxides with acid i.e. hydrochloric acid produces hydrogen peroxide. The formation of peroxides is feasible with hydrogen, alkali and alkaline earth metals.

Complete answer:
Peroxides are formed by the treatment of metallic oxides with acid i.e. hydrochloric acid. The molecular formula of peroxide ion is ${{O}_{2}}^{2-}$. The structure of hydrogen peroxide is given in the following diagram:

From the above diagram, we conclude that in peroxides, there is a single bond present between two oxygen atoms and charge on each oxygen atom is $-1$. Let us now consider the structure of $Pb{{O}_{2}}$ which is described in the following diagram-

From the above structure, we conclude that $O-O$bond is not present in $Pb{{O}_{2}}$ . In $Pb{{O}_{2}}$ , lead is present in $+4$ oxidation state while each oxygen atom carries a $-2$ charge.
Therefore, $Pb{{O}_{2}}$ is not a peroxide.

Additional information:
The chemical name of $Pb{{O}_{2}}$ is lead dioxide. The electronic configuration of lead is $[Xe]6{{s}^{2}}4{{f}^{14}}5{{d}^{10}}6{{p}^{2}}$. Considering the electronic configuration into the account, the oxidation state of lead should be $+2$ and $+4$. Due to the inert pair effect, $+2$oxidation state of lead is more stable in comparison to $+4$ . As a consequence, $PbO$ is much more stable than $Pb{{O}_{2}}$.

Note:
It is important to note that the structure of $Pb{{O}_{2}}$ doesn’t contain $O-O$ bond. Hence, $Pb{{O}_{2}}$ is not a peroxide. In $Pb{{O}_{2}}$ , lead is present in $+4$ oxidation state while each oxygen atom carries a $-2$ charge.