Chapter 6.4, Problem 5PPC

(a)

Interpretation Introduction

Interpretation:

The formal charges of element A if it was in (a) Group 7A, (b) Group 5A, (c) Group 3A should be drawn.

Concept Introduction

• A formal charge (FC) is the charge assigned to an atom in a molecule, irrespective of relative electronegativity by thinking that electrons in all chemical bonds are shared equally among atoms.
• This method is used to identify the most probable Lewis structures if more than one possibility exists for a compound.
• Formal charge of an atom can be determined by the given formula.

$\text{Formal}\text{charge}\left(\text{F}\text{C}\right)\text{=}\left(\begin{array}{l}\text{no}\text{.of}\text{valence}\\ \text{electron}\text{in}\text{atom}\end{array}\right)-\frac{\text{1}}{\text{2}}\left(\begin{array}{l}\text{no}\text{.of}\text{bonding}\\ \text{electrons}\end{array}\right)-\left(\begin{array}{l}\text{no}\text{.of}\text{non-bonding}\\ \text{electrons}\end{array}\right)$

To determine: Formal charge of the given species

Answer to Problem 5PPC

Explanation of Solution

Given Lewis structure

A formal charge (FC) is the charge assigned to an atom in a molecule, irrespective of relative electronegativity.

The formal charge of the given species is calculated,

• If A is group 7A, then number of valence electrons is 7

$\begin{array}{c}\text{Number}\text{of}\text{valence}\text{electron=}\text{7}\\ \text{Number}\text{of}\text{bonding}\text{electron=}2\\ \text{Number}\text{of}\text{non-bonding}\text{electron}\text{=}6\end{array}$

Substituting these values to the equation,

$\begin{array}{c}\text{FC}\text{=}7-\left(\frac{\text{1}}{\text{2}}\text{×2}\right)-6\\ \text{=}0\end{array}$

• If A is group 5A, then number of valence electrons is 5

$\begin{array}{c}\text{Number}\text{of}\text{valence}\text{electron}\text{=}5\\ \text{Number}\text{of}\text{bonding}\text{electron}\text{=}2\\ \text{Number}\text{of}\text{non-bonding}\text{electron}\text{=}6\end{array}$

Substituting these values to the equation,

$\begin{array}{c}\text{FC}\text{=}5-\left(\frac{\text{1}}{\text{2}}\text{×2}\right)-6\\ \text{=}-2\end{array}$

• If A is group 3A, then number of valence electrons is 3

$\begin{array}{c}\text{Number}\text{of}\text{valence}\text{electron}\text{=}3\\ \text{Number}\text{of}\text{bonding}\text{electron}\text{=}2\\ \text{Number}\text{of}\text{non-bonding}\text{electron}\text{=}6\end{array}$

Substituting these values to the equation,

$\begin{array}{c}\text{FC}\text{=}3-\left(\frac{\text{1}}{\text{2}}\text{×2}\right)-6\\ \text{=}-4\end{array}$

Therefore,

The formal charges are,

(b)

Interpretation Introduction

Interpretation:

The formal charges of element A if it was in (a) Group 7A, (b) Group 5A, (c) Group 3A should be drawn.

Concept Introduction

• A formal charge (FC) is the charge assigned to an atom in a molecule, irrespective of relative electronegativity by thinking that electrons in all chemical bonds are shared equally among atoms.
• This method is used to identify the most probable Lewis structures if more than one possibility exists for a compound.
• Formal charge of an atom can be determined by the given formula.

$\text{Formal}\text{charge}\left(\text{F}\text{C}\right)\text{=}\left(\begin{array}{l}\text{no}\text{.of}\text{valence}\\ \text{electron}\text{in}\text{atom}\end{array}\right)-\frac{\text{1}}{\text{2}}\left(\begin{array}{l}\text{no}\text{.of}\text{bonding}\\ \text{electrons}\end{array}\right)-\left(\begin{array}{l}\text{no}\text{.of}\text{non-bonding}\\ \text{electrons}\end{array}\right)$

To determine: Formal charge of the given species

Answer to Problem 5PPC

Explanation of Solution

Given Lewis structure

A formal charge (FC) is the charge assigned to an atom in a molecule, irrespective of relative electronegativity.

The formal charge of the given species is calculated,

• If A is group 7A, then number of valence electrons is 7

$\begin{array}{c}\text{Number}\text{of}\text{valence}\text{electron=}\text{7}\\ \text{Number}\text{of}\text{bonding}\text{electron=}4\\ \text{Number}\text{of}\text{non-bonding}\text{electron}\text{=}4\end{array}$

Substituting these values to the equation,

$\begin{array}{c}\text{FC}\text{=}7-\left(\frac{\text{1}}{\text{2}}\text{×4}\right)-4\\ =+1\end{array}$

• If A is group 5A, then number of valence electrons is 5

$\begin{array}{c}\text{Number}\text{of}\text{valence}\text{electron}\text{=}5\\ \text{Number}\text{of}\text{bonding}\text{electron}\text{=}4\\ \text{Number}\text{of}\text{non-bonding}\text{electron}\text{=}4\end{array}$

Substituting these values to the equation,

$\begin{array}{c}\text{FC}\text{=}5-\left(\frac{\text{1}}{\text{2}}\text{×4}\right)-4\\ \text{=}-1\end{array}$

• If A is group 3A, then number of valence electrons is 3

$\begin{array}{c}\text{Number}\text{of}\text{valence}\text{electron}\text{=}3\\ \text{Number}\text{of}\text{bonding}\text{electron}\text{=}4\\ \text{Number}\text{of}\text{non-bonding}\text{electron}\text{=}4\end{array}$

Substituting these values to the equation,

$\begin{array}{c}\text{FC}\text{=}3-\left(\frac{\text{1}}{\text{2}}\text{×4}\right)-4\\ \text{=}-3\end{array}$

Therefore,

The formal charges are,

(c)

Interpretation Introduction

Interpretation:

The formal charges of element A if it was in (a) Group 7A, (b) Group 5A, (c) Group 3A should be drawn.

Concept Introduction

• A formal charge (FC) is the charge assigned to an atom in a molecule, irrespective of relative electronegativity by thinking that electrons in all chemical bonds are shared equally among atoms.
• This method is used to identify the most probable Lewis structures if more than one possibility exists for a compound.
• Formal charge of an atom can be determined by the given formula.

$\text{Formal}\text{charge}\left(\text{F}\text{C}\right)\text{=}\left(\begin{array}{l}\text{no}\text{.of}\text{valence}\\ \text{electron}\text{in}\text{atom}\end{array}\right)-\frac{\text{1}}{\text{2}}\left(\begin{array}{l}\text{no}\text{.of}\text{bonding}\\ \text{electrons}\end{array}\right)-\left(\begin{array}{l}\text{no}\text{.of}\text{non-bonding}\\ \text{electrons}\end{array}\right)$

To determine: Formal charge of the given species

Answer to Problem 5PPC

Explanation of Solution

Given Lewis structure

A formal charge (FC) is the charge assigned to an atom in a molecule, irrespective of relative electronegativity.

The formal charge of the given species is calculated,

• If A is group 7A, then number of valence electrons is 7

$\begin{array}{c}\text{Number}\text{of}\text{valence}\text{electron=}\text{7}\\ \text{Number}\text{of}\text{bonding}\text{electron=}6\\ \text{Number}\text{of}\text{non-bonding}\text{electron}\text{=}2\end{array}$

Substituting these values to the equation,

$\begin{array}{c}\text{FC}\text{=}7-\left(\frac{\text{1}}{\text{2}}\text{×6}\right)-2\\ =+2\end{array}$

• If A is group 5A, then number of valence electrons is 5

$\begin{array}{c}\text{Number}\text{of}\text{valence}\text{electron}\text{=}5\\ \text{Number}\text{of}\text{bonding}\text{electron}\text{=}6\\ \text{Number}\text{of}\text{non-bonding}\text{electron}\text{=}2\end{array}$

Substituting these values to the equation,

$\begin{array}{c}\text{FC}\text{=}5-\left(\frac{\text{1}}{\text{2}}\text{×6}\right)-2\\ \text{=}0\end{array}$

• If A is group 3A, then number of valence electrons is 3

$\begin{array}{c}\text{Number}\text{of}\text{valence}\text{electron}\text{=}3\\ \text{Number}\text{of}\text{bonding}\text{electron}\text{=}6\\ \text{Number}\text{of}\text{non-bonding}\text{electron}\text{=}2\end{array}$

Substituting these values to the equation,

$\begin{array}{c}\text{FC}\text{=}3-\left(\frac{\text{1}}{\text{2}}\text{×6}\right)-2\\ \text{=}-2\end{array}$

Therefore,

The formal charges are,