Q.6.58 - An Introduction to General, Organic, and Biological Chemistry

Question

Determine the total number of valence electrons for each of the following:

a. ${\mathrm{SBr}}_2$

b. ${\mathrm{NBr}}_3$

c. ${\mathrm{CH}}_3\mathrm{OH}$

Step-by-Step Solution

Answer

a. The total number of valence electrons in ${\mathrm{SBr}}_2$ are 20.

b. The total number of valence electrons in ${\mathrm{NBr}}_3$ are 26.

c. The total number of valence electrons in data-custom-editor="chemistry" ${\mathrm{CH}}_3\mathrm{OH}$ are 14.

Step 1: Part (a) Given Information

To determine the number of valence electrons in ${\mathrm{SBr}}_2$

Step 2: Part (a) Explanation

The electrons that are present in an outermost shell of an atom are known as Valence electrons.

In ${\mathrm{SBr}}_2$ , the central atom is sulfur, and the number of valence electrons present in sulfur is 6 while the two bromine atoms have seven valence electrons each.

Thus, the total number of valence electrons in ${\mathrm{SBr}}_2$ is as follows:

$$\begin{gathered} \mathrm{Total} \mathrm{number} \mathrm{of} \mathrm{valence} \mathrm{electrons}=\mathrm{Valence} {\mathrm{e}}^{-} \mathrm{of} \mathrm{S} +2 \times \mathrm{Valence} {\mathrm{e}}^{-} \mathrm{of} \mathrm{Br} \\ =6 {\mathrm{e}}^{-}+ \left(2\times 7\right) {\mathrm{e}}^{-} \\ =6 {\mathrm{e}}^{-}+14 {\mathrm{e}}^{-} \\ = 20 {\mathrm{e}}^{-} \end{gathered}$$

Hence, the total number of valence electrons in ${\mathrm{SBr}}_2$ are 20.

Step 1: Part (b) Given Information

To determine the number of valence electrons for ${\mathrm{NBr}}_3$.

Step 2: Part (b) Explanation

The electrons that are present in an outermost shell of an atom are known as Valence electrons.

In ${\mathrm{NBr}}_3$ , the central atom is nitrogen, and the number of valence electrons present in nitrogen is 5 while the three bromine atoms have seven valence electrons each.

Thus, the total number of valence electrons in ${\mathrm{NBr}}_3$ is as follows:

$$\begin{gathered} \mathrm{Total} \mathrm{number} \mathrm{of} \mathrm{valence} \mathrm{electrons}=\mathrm{Valence} {\mathrm{e}}^{-} \mathrm{of} \mathrm{N} +3 \times \mathrm{Valence} {\mathrm{e}}^{-} \mathrm{of} \mathrm{Br} \\ =5 {\mathrm{e}}^{-}+ \left(3\times 7\right) {\mathrm{e}}^{-} \\ =5 {\mathrm{e}}^{-}+21 {\mathrm{e}}^{-} \\ = 26 {\mathrm{e}}^{-} \end{gathered}$$

Hence, the total number of valence electrons in ${\mathrm{NBr}}_3$ are 26.

Step 1: Part (c) Given Information

To determine the number of valence electrons in ${\mathrm{CH}}_3\mathrm{OH}$.

Step 2: Part (c) Explanation

The electrons that are present in an outermost shell of an atom are known as Valence electrons.

In ${\mathrm{CH}}_3\mathrm{OH}$ , the central atom is carbon, and the number of valence electrons present in carbon is 4 while four hydrogen atoms have one valence electron each and the number of valence electrons of oxygen are 6.

Thus, the total number of valence electrons in ${\mathrm{CH}}_3\mathrm{OH}$ is as follows:

$$\begin{gathered} \mathrm{Total} \mathrm{number} \mathrm{of} \mathrm{valence} \mathrm{electrons}=\mathrm{Valence} {\mathrm{e}}^{-} \mathrm{of} \mathrm{C} +4\times \mathrm{Valence} {\mathrm{e}}^{-} \mathrm{of} \mathrm{H}+ \mathrm{Valence} {\mathrm{e}}^{-} \mathrm{of} \mathrm{O} \\ =4 {\mathrm{e}}^{-}+ \left(4\times 1\right) {\mathrm{e}}^{-}+6 {\mathrm{e}}^{-} \\ =4 {\mathrm{e}}^{-}+4 {\mathrm{e}}^{-}+6 {\mathrm{e}}^{-} \\ =14 {\mathrm{e}}^{-} \end{gathered}$$

Hence, the total number of valence electrons in ${\mathrm{CH}}_3\mathrm{OH}$ are 14.