Question

What is the oxidation number of N in ${\mathrm{NaNO}}_3$?

Answer 1

1. The oxidation number of any compound, element, or atom indicates the number of electrons lost or gain from the valence shell.
2. Thus, they become stable by attaining the stable configuration.

Oxidation number of elements

• Sodium is an electropositive element and thus, the oxidation number of Sodium is +1.
• As Sodium loses its 1 electron to obtain the stable noble gas configuration.
• Oxygen is the second most electronegative element.
• Oxygen gains two electrons to achieve a stable configuration, and therefore the oxidation number is -2.

Calculating the oxidation number of Nitrogen

• Let the oxidation number of Nitrogen be x.
• Equating all the atoms to 0
• $\left(\mathrm{No}.\mathrm{of}\mathrm{Sodium}\mathrm{atom}\right)\left(\mathrm{Oxidation}\mathrm{No}.\mathrm{of}\mathrm{Sodium}\right)+\left(\mathrm{No}.\mathrm{of}\mathrm{Nitrogen}\mathrm{atom}\right)\left(\mathrm{Oxidation}\mathrm{No}.\mathrm{of}\mathrm{Nitrogen}\right)+\left(\mathrm{No}.\mathrm{of}\mathrm{Oxygen}\mathrm{atom}\right)\left(\mathrm{Oxidation}\mathrm{No}.\mathrm{of}\mathrm{Oxygen}\right)=0$$1\left(1\right)+1\left(\mathrm{x}\right)+3\left(-2\right)=0$
• $\mathrm{x}=+5$
• Therefore, the oxidation state of $\mathrm{N}$ in $\left({\mathrm{NaNO}}_3\right)$is +5.