Q. 8.156 - An Introduction to General, Organic, and Biological Chemistry

Question

Classify each of the following molecules as polar or nonpolar:$\left(6.7 ,6.8 ,6.9\right)$

a. $N_2$

b. $N{H}_{2}Cl$

Step-by-Step Solution

Answer

a. The molecule $N_2$ is nonpolar.

b. The molecule $N{H}_{2}Cl$ is polar.

Part (a) step 1: Given Information

We need to classify whether the molecule $N_2$ is polar or nonpolar.

Part (a) step 2: Explanation

A polar molecule is a molecule where there is a net electronegative difference within the molecule. There is a net electronegative difference when the polar bonds in the molecule are not symmetric.

If there is no net electronegative difference, then the molecule is nonpolar.

The electronegative of $N$ is $3.0$. So both atom in the molecule are $N$ atoms, the electronegativity difference between the atom is $0.0$ making the bond nonpolar covalent.

Part (b) step 1: Given Information

We need to classify whether the molecule $N{H}_{2}Cl$ is polar or nonpolar.

Part (b) step 2: Explanation

Here, identify the total number of valence electrons in each molecule. 

$H$  is in group $1A$, it means it has $1$ valence.

$N$ is in group $5A$,  it means it has $5$ valence.

$Cl$ is in group $7A$, it means it has $7$ valence.

The total number of valence electrons. 

$$\begin{gathered} total VE=2\times 1+5+7 \\ =2+12 \\ =14 \end{gathered}$$

the total valence electrons is $14$.

the central atom is  $N$In order to complete the octet of the  $N and Cl$

atoms, there should be a single bond between the $N and Cl$ atoms and single bonds in $N and H$ atoms.

Therefore, the Lewis structure of the molecule should be:

According to the VSEPR theory is trigonal pyramidal, and the molecule is polar. The uneven distribution of electron density.