Question

What is the oxidation state of $ Pb $ in $ Pb{{O}_{2}} $ ?

Answer 1

Hint :We know that Oxidation number is the number of electrons gained or lost by the atoms. The charge represents the oxidation number of an atom. Oxidation number exhibited by oxygen is $ -2 $ as in this compound oxygen is not in the form of peroxide or superoxide.

Complete Step By Step Answer:
An atom loses or gains electrons to form a bond with other atoms. So, the atoms get charged known as ions. The superscript of the ions represents the oxidation number of that atom. In neutral molecules, the sum of the oxidation number is equal to zero. In charged molecules, the sum of the oxidation number is equal to the charge of the molecule. The atoms in elemental numbers have zero oxidation number.
Let us know some rules for finding oxidation state before solving it:
-The oxidation number of elements in its elemental form is always $ 0. $
-The oxidation number of a monatomic ion equals the charge of the ion.
-The oxidation number of $ H $ is $ +1 $ but it is $ -1 $ in when combined with less electronegative elements.
-The oxidation number of $ O $ in compounds is usually $ -2, $ but it is $ -1 $ in peroxides.
-The oxidation number of a Group $ 1 $ element in a compound is $ +1. $
-The oxidation number of a Group $ 2 $ element in a compound is $ +2. $
-The oxidation number of a Group $ 17 $ element in a binary compound is $ -1. $
-The sum of the oxidation numbers of all of the atoms in a neutral compound is $ 0. $
-The sum of the oxidation numbers in a polyatomic ion is equal to the charge of the ion.
Now going on to our question, which is to find the oxidation number or oxidation state of $ Pb $ in $ Pb{{O}_{2}} $ . So we will let the oxidation number of $ Pb $ be $ x $ . And the oxidation number exhibited by oxygen is $ -2 $ . And the whole compound is neutral so the sum of the oxidation number of all the atoms should be zero.
  $ \Rightarrow x+(-2)+(-2)=0 $
On further solving we get;
 $ \Rightarrow x=+4 $
Hence oxidation number of $ Pb $ in $ Pb{{O}_{2}} $ is $ +4 $ .

Note :
Remember that $ Pb{{O}_{2}} $ is also known as Lead peroxide. The oxygen in peroxides always has $ -\text{ }1 $ oxidation number. In a molecule, the more electronegative atom has a negative oxidation number, and less electronegative has a positive oxidation number.