Chapter 1, Problem 1.39P

Assign formal charges to each carbon atom in the given species. All lone pairs have been drawn in.

a. ${\text{CH}}_{\text{2}}=\stackrel{··}{\text{C}}\text{H}$ b. $\text{H}-\stackrel{··}{\text{C}}-\text{H}$ c. d.

Interpretation Introduction

(a)

Interpretation: The formal charge on each carbon atom in the given species is to be assigned.

Concept introduction: The formal charge on an atom is calculated by the formula,

$\text{Formal charge}=\text{Valence electrons}-\left[\text{Nonbonding electrons}+\frac{1}{2}\left(\text{Bonding electrons}\right)\right]$

Answer to Problem 1.39P

In the given species, the formal charge on carbon atom of ${\text{CH}}_{\text{2}}$ is zero and the formal charge on carbon atom of $\stackrel{··}{\text{C}}\text{H}$ is $-\text{1}$ as shown below.

$\underset{0}{\text{C}}{\text{H}}_{\text{2}}\text{=}\underset{-1}{\overset{··}{\text{C}}}\text{H}$

Explanation of Solution

The given species is ${\text{CH}}_{\text{2}}\text{=}\stackrel{··}{\text{C}}\text{H}$.

The formal charge on an atom is calculated by the formula,

$\text{Formal charge}=\text{Valence electrons}-\left[\text{Nonbonding electrons}+\frac{1}{2}\left(\text{Bonding electrons}\right)\right]$ For the carbon present in ${\text{CH}}_{\text{2}}$,

$\begin{array}{rll}\text{Number}\text{of}\text{valence}\text{electrons}& =& \text{4}\\ \text{Number}\text{of}\text{bonding}\text{electrons}& =& 8\\ \text{Number}\text{of}\text{nonbonding}\text{electrons}& =& 0\end{array}$

Substitute these values in the above equation to calculate the formal charge. $\begin{array}{rll}\text{Formal charge}& =& \text{4}-\left[\text{0}+\frac{1}{2}\times \text{8}\right]\\ & =& 4-4\\ & =& 0\end{array}$

For the carbon present in $\stackrel{··}{-\text{C}}\text{H}$,

$\begin{array}{rll}\text{Number}\text{of}\text{valence}\text{electrons}& =& \text{4}\\ \text{Number}\text{of}\text{bonding}\text{electrons}& =& 6\\ \text{Number}\text{of}\text{nonbonding}\text{electrons}& =& 2\end{array}$

Substitute these values in above equation to calculate the formal charge on the carbon of $\stackrel{··}{\text{C}}\text{H}$.

$\begin{array}{rll}\text{Formal charge}& =& \text{4}-\left[\text{2}+\frac{1}{2}\times \text{6}\right]\\ & =& 4-5\\ & =& -1\end{array}$

Thus, in the given species, the formal charge on carbon atom of ${\text{CH}}_{\text{2}}$ is zero and the formal charge on the carbon atom of $\stackrel{··}{\text{C}}\text{H}$ is $-\text{1}$.

Conclusion

(a) In the given species, the formal charge on carbon atom of ${\text{CH}}_{\text{2}}$ is zero and the formal charge on carbon atom of $\stackrel{··}{\text{C}}\text{H}$ is $-\text{1}$.

Interpretation Introduction

(b)

Interpretation: The formal charge on each carbon atom in the given species is to be assigned.

Concept introduction: The formal charge on an atom is calculated by the formula, $\text{Formal charge}=\text{Valence electrons}-\left[\text{Nonbonding electrons}+\frac{1}{2}\left(\text{Bonding electrons}\right)\right]$

Answer to Problem 1.39P

In the given species, the formal charge on carbon atom is zero as shown below.

$\text{H}-\stackrel{··}{\underset{0}{\text{C}}}-\text{H}$

Explanation of Solution

The given species is $\text{H}-\stackrel{··}{\text{C}}-\text{H}$.

The formal charge on an atom is calculated by the formula,

$\text{Formal charge}=\text{Valence electrons}-\left[\text{Nonbonding electrons}+\frac{1}{2}\left(\text{Bonding electrons}\right)\right]$ For the given carbon atom,

$\begin{array}{rll}\text{Number}\text{of}\text{valence}\text{electrons}& =& \text{4}\\ \text{Number}\text{of}\text{bonding}\text{electrons}& =& 4\\ \text{Number}\text{of}\text{nonbonding}\text{electrons}& =& 2\end{array}$

Substitute these values in above equation to calculate the formal charge on carbon atom. $\begin{array}{rll}\text{Formal charge}& =& \text{4}-\left[\text{2}+\frac{1}{2}\times \text{4}\right]\\ & =& 4-4\\ & =& 0\end{array}$

Thus, in the given species, the formal charge on carbon atom is zero.

Conclusion

In the given species, the formal charge on carbon atom is zero.

Interpretation Introduction

(c)

Interpretation: The formal charge on each carbon atom in the given species is to be assigned.

Concept introduction: The formal charge on an atom is calculated by the formula,

$\text{Formal charge}=\text{Valence electrons}-\left[\text{Nonbonding electrons}+\frac{1}{2}\left(\text{Bonding electrons}\right)\right]$

Answer to Problem 1.39P

In the given species, the formal charge on carbon atom is zero as shown below.

Explanation of Solution

The given species is,

Figure 1

The formal charge on an atom is calculated by the formula,

$\text{Formal charge}=\text{Valence electrons}-\left[\text{Nonbonding electrons}+\frac{1}{2}\left(\text{Bonding electrons}\right)\right]$

For the given carbon atom,

$\begin{array}{rll}\text{Number}\text{of}\text{valence}\text{electrons}& =& \text{4}\\ \text{Number}\text{of}\text{bonding}\text{electrons}& =& 6\\ \text{Number}\text{of}\text{nonbonding}\text{electrons}& =& 1\end{array}$

Substitute these values in above equation, to calculate the formal charge on carbon atom. $\begin{array}{rll}\text{Formal charge}& =& \text{4}-\left[\text{1}+\frac{1}{2}\times \text{6}\right]\\ & =& 4-4\\ & =& 0\end{array}$

Thus, in the given species, the formal charge on carbon atom is zero.

Figure 2

Conclusion

In the given species, the formal charge on carbon atom is zero.

Interpretation Introduction

(d)

Interpretation: The formal charge on each carbon atom in the given species is to be assigned.

Concept introduction: The formal charge on an atom is calculated by the formula,

$\text{Formal charge}=\text{Valence electrons}-\left[\text{Nonbonding electrons}+\frac{1}{2}\left(\text{Bonding electrons}\right)\right]$

Answer to Problem 1.39P

In the given species, the formal charge on carbon atom of ${\text{H}}_3\text{C}$ is zero and the formal charge on carbon atom of ${\text{CH}}_{\text{2}}$ is $+\text{1}$ as shown below.

Explanation of Solution

The given species is,

Figure 3

The formal charge on an atom is calculated by the formula,

$\text{Formal charge}=\text{Valence electrons}-\left[\text{Nonbonding electrons}+\frac{1}{2}\left(\text{Bonding electrons}\right)\right]$ For the carbon of ${\text{CH}}_3$.

$\begin{array}{rll}\text{Number}\text{of}\text{valence}\text{electrons}& =& \text{4}\\ \text{Number}\text{of}\text{bonding}\text{electrons}& =& 8\\ \text{Number}\text{of}\text{nonbonding}\text{electrons}& =& 0\end{array}$

Substitute these value in above equation to calculate the formal charge on the carbon of ${\text{CH}}_{\text{2}}$.

$\begin{array}{rll}\text{Formal charge}& =& \text{4}-\left[\text{0}+\frac{1}{2}\times \text{8}\right]\\ & =& 4-4\\ & =& 0\end{array}$

For the carbon of ${\text{CH}}_2$.

$\begin{array}{rll}\text{Number}\text{of}\text{valence}\text{electrons}& =& \text{4}\\ \text{Number}\text{of}\text{bonding}\text{electrons}& =& 6\\ \text{Number}\text{of}\text{nonbonding}\text{electrons}& =& 0\end{array}$

Substitute these value in above equation to calculate the formal charge on the carbon of ${\text{CH}}_2$.

$\begin{array}{rll}\text{Formal charge}& =& \text{4}-\left[\text{0}+\frac{1}{2}\times \text{6}\right]\\ & =& 4-3\\ & =& +1\end{array}$

Thus, in the given species, the formal charge on carbon atom of ${\text{H}}_3\text{C}$ is zero and the formal charge on carbon atom of ${\text{CH}}_{\text{2}}$ is $+\text{1}$ as shown below.

Figure 4

Conclusion

In the given species, the formal charge on carbon atom of ${\text{H}}_3\text{C}$ is zero and the formal charge on carbon atom of ${\text{CH}}_{\text{2}}$ is $+\text{1}$.