Question

What is the valency of N in $\mathrm{NO},{\mathrm{N}}_2\mathrm{O}$ and ${\mathrm{NO}}_2$?

Answer 1

Valency:

• “Valency is the combining capacity of an atom.”
• “The electrons present in the outermost shell of an atom are known as the valence electrons.”

Valency of N in $\mathbf{NO}\mathbf{,}\mathbf{}{\mathbf{N}}_{\mathbf{2}}\mathbf{O}$ and ${\mathbf{NO}}_{\mathbf{2}}$:

• In order to find the valency of N, consider the valency of N in each compound as “x”. The valency of oxygen is $2$. Since oxygen gains $2$ electrons to become stable, its oxidation state is $-2$.
• All the three given compound is neutral. So the net charge of the compound can be equated to zero.

Valency of N in $\mathbf{NO}$:

$$\begin{gathered} \left(\mathrm{Number}\mathrm{of}\mathrm{nitrogen}\times \mathrm{Charge}\mathrm{of}\mathrm{nitrogen}\right)+\left(\mathrm{Number}\mathrm{of}\mathrm{oxygen}\times \mathrm{Charge}\mathrm{of}\mathrm{oxygen}\right)=0 \\ (1\times \mathrm{x})+\left(1\times -2\right)=0 \\ \mathrm{x}+\left(-2\right)=0 \\ \mathrm{x}=+2 \end{gathered}$$

Hence, the valency of N in $\mathrm{NO}$ is $2$.

Valency of N in ${\mathbf{N}}_{\mathbf{2}}\mathbf{O}$ :

$$\begin{gathered} \left(2\times x\right)+(1\times -2)=0 \\ 2x+(-2)=0 \\ 2x=2 \\ x=\frac{2}{2}=1 \end{gathered}$$

Hence, the valency of N in ${\mathrm{N}}_2\mathrm{O}$ is $1$.

Valency of N in ${\mathbf{NO}}_{\mathbf{2}}$:

$$\begin{gathered} \left(1\times x\right)+\left(2\times -2\right)=0 \\ x+(-4)=0 \\ x=+4 \end{gathered}$$

Hence, the valency of N in ${\mathrm{NO}}_2$ is $4$.