Question

What is the valency of $N$ in $NO$ , ${N_2}O$ and $N{O_2}$ ?

Answer 1

Hint : In order to determine the valency of the given compounds, we need to consider the oxidation state of both nitrogen and oxygen. An element’s valence is the number of hydrogen atoms which can combine with or replace one of the element’s atoms.

Complete Step By Step Answer:
Let us assume the valency of nitrogen to be $X$ .As we know that the valency of oxygen is $+ 2$ , we can individually find the valency of $N$ in given compounds.
So, by substituting the value of oxygen, we can find valency of Nitrogen.
In $NO$ , one atom of nitrogen has combined with one atom of oxygen,
$X + [1 \times ( - 2)] = 0$
$X = + 2$
Valency of Nitrogen in $NO$ is $+ 2$ .
In ${N_2}O$ ,two atoms of nitrogen combine with one atom of oxygen,
$2X + [1 \times ( - 2)] = 0$
$X = + 1$
Valency of Nitrogen in ${N_2}O$ is $+ 1$ .
In $N{O_2}$ , one atom of nitrogen combines with two atoms of oxygen,
$X + [2 \times ( - 2)] = 0$
$X = + 4$
Valency of Nitrogen in $N{O_2}$ is $+ 4$ .
Hence , the valency of $N$ in $NO$ is $+ 2$ , valency of $N$ in ${N_2}O$ is $+ 1$ ,valency of $N$ in $N{O_2}$ is $+ 4$ .

Note :
If the number of electrons present in the outer shell is between one to four, the compound is said to have positive valency. Compounds that have four, five, six, or seven electrons the valency is determined by subtracting the electron from eight. All noble gases except for Helium are known to have eight electrons.