1. Rules to Remember
* Oxygen's oxidation number is usually -2, except in peroxides (like H₂O₂) where it's -1.
* The sum of the oxidation numbers in a neutral compound is 0.
2. Applying the Rules
* We have three oxygen atoms (O) with an oxidation number of -2 each, giving a total of -6.
* To balance this, the two nitrogen atoms (N) must have a combined oxidation number of +6.
* Therefore, each nitrogen atom has an oxidation number of +3.
Conclusion
The oxidation number of nitrogen (N) in N₂O₃ is +3.
