Chapter 13, Problem 1ASA

First you need to find the number of valence electrons in ${\text{NH}}_{\text{2}}\text{Cl}$. For counting purposes with Lewis structures, the number of valence electrons in an atom of a main group element is equal to the last digit in the group number of that element in the Periodic Table.

$\text{N}$ is in Group ________ $\text{H}$ is in Group ________ $\text{Cl}$ is in Group _________

In ${\text{NH}}_{\text{2}}\text{Cl}$ there is a total of ____________ valence electrons.

Interpretation Introduction

Interpretation:

The given blanks are to be filled.

Concept introduction:

The periodic table represents elements in order of their atomic number. In the modern periodic table, the horizontal rows are known as periods and vertical columns are known as groups. There are seven periods and eighteenth groups in the modern periodic table. The valence electron of an element is the number of electrons present in the last shell of an atom of that element.

Answer to Problem 1ASA

Nitrogen $\left(\text{N}\right)$ is in Group 15 hydrogen $\left(\text{H}\right)$ is in Group 1 chorine $\left(\text{Cl}\right)$ is in Group 17

In ${\text{NH}}_{\text{2}}\text{Cl}$ there is a total of 14 valence electrons.

Explanation of Solution

The nitrogen belongs to the group $15$. The number of valance electrons in nitrogen atom is $5$.

The chlorine belongs to the group $17$. The number of valance electrons in nitrogen atom is $7$.

The hydrogen belongs to the group $1$. The number of valence electrons in the hydrogen atom is $1$.

The total number of valance electrons in ${\text{NH}}_{\text{2}}\text{Cl}$ is calculated as shown below.

$N_{\text{e}}=N_{\text{N}}+2N_{\text{H}}+N_{\text{Cl}}$

Where,

• $N_{\text{N}}$ is the number of valence electrons in a nitrogen atom.
• $N_{\text{H}}$ is the number of valence electrons in a hydrogen atom.
• $N_{\text{Cl}}$ is the number of valence electrons in a chlorine atom.

Substitute the value of $N_{\text{N}}$, $N_{\text{H}}$ and $N_{\text{Cl}}$ in the above equation.

$\begin{array}{rll}{N}_{\text{e}}& =& 5+2\left(1\right)+\left(7\right)\\ & =& 5+2+7\\ & =& 14\end{array}$

Therefore, the completed sentences are as follows.

Nitrogen $\left(\text{N}\right)$ is in Group 15 hydrogen $\left(\text{H}\right)$ is in Group 1 chorine $\left(\text{Cl}\right)$ is in Group 17

In ${\text{NH}}_{\text{2}}\text{Cl}$ there is a total of 14 valence electrons.

Conclusion

The number of valance electron in ${\text{NH}}_{\text{2}}\text{Cl}$$14$.