Question

What is the sum of the oxidation numbers in a polyatomic ion?

Answer 1

An element while forming a chemical bond, it is going to accept or donate or share the electrons with other elements and it is called the oxidation number of the particular element in the respective compound.

Complete answer:
- In the question it is asked what the sum of the oxidation number is in a polyatomic ion.
- We know that in a molecule every element has some oxidation number.
- Without having the oxidation numbers the molecule is not going to exist.
- We should know the oxidation number of each and every element in the molecule to calculate the oxidation number of the polyatomic ion.
- The sum of the oxidation number of all the elements in the molecule is going to give the information about the net charge in the polyatomic ion.
- For example take $PO_{4}^{3-}$, here the net charge on the phosphate ion is ‘-3’.
- See how we can calculate the net charge of the polyatomic ion by using the oxidation number of each element involved in int.
- We know that each oxygen has an oxidation number of ‘-2’ and the phosphorus atom has an oxidation number of ‘+5’.
- Now we can find the net charge on the phosphate ion by using the oxidation numbers of each element involved in phosphate anion.
4(O) + 1 (P) = 4(-2) + (5) = -3.
- Therefore the sum of the oxidation number of all the elements in a polyatomic ion will give the net charge of the polyatomic ion.

Note:
We should know the oxidation number of each and every element present in a molecule to calculate the net charge of the particular ion otherwise it is very difficult to find the net charge of the polyatomic ion.