Chapter 12, Problem 20A

(a)

Interpretation Introduction

Interpretation:

The electronic configuration of given atom and its most stable ion is to be written.

Concept introduction:

The electronic configuration is the arrangement of electrons in an atom. The atoms lose or gain electrons to acquire noble gas configuration because the ion which achievesthe nearest noble gas configuration is most stable.

Answer to Problem 20A

Electronic configuration of $\mathrm{L}\mathrm{i}$ according to Aufbau’s Principle is:

  $1{\mathrm{s}}^{2}2{\mathrm{s}}^1$

Therefore, Electronic configuration of $\mathrm{L}{\mathrm{i}}^{+}$ :

  $1{\mathrm{s}}^2$

It attains configuration as $\mathrm{H}\mathrm{e}$

Explanation of Solution

Lithium belongs to ist group. So, it has a tendency to lose one electron and form the most stable ion $\mathrm{L}{\mathrm{i}}^{+}$ .

(b)

Interpretation Introduction

Interpretation:

The electronic configuration of given atom and its most stable ion is to be written.

Concept introduction:

The electronic configuration is the arrangement of electrons in an atom. The atoms lose or gain electrons to acquire noble gas configuration because the ion which achievesthe nearest noble gas configuration is most stable.

Answer to Problem 20A

Electronic configuration of $\mathrm{B}\mathrm{r}$ according to Aufbau’s Principle is:

  $\left[\mathrm{A}\mathrm{r}\right]4{\mathrm{s}}^{2}3{\mathrm{d}}^{10}4{\mathrm{p}}^5$

Therefore, Electronic configuration of $\mathrm{B}{\mathrm{r}}^{-}$ :

  $\left[\mathrm{A}\mathrm{r}\right]4{\mathrm{s}}^{2}3{\mathrm{d}}^{10}4{\mathrm{p}}^6$

It attains configuration as $\mathrm{K}\mathrm{r}$

Explanation of Solution

Bromine belongs to the 17^th group. So it has a tendency to gain one electron and form the most stable ion $\mathrm{B}{\mathrm{r}}^{-}$ .

Electronic configuration of $\mathrm{B}\mathrm{r}$ according to Aufbau’s Principle is:

  $\left[\mathrm{A}\mathrm{r}\right]4{\mathrm{s}}^{2}3{\mathrm{d}}^{10}4{\mathrm{p}}^5$

Therefore, Electronic configuration of $\mathrm{B}{\mathrm{r}}^{-}$ :

  $\left[\mathrm{A}\mathrm{r}\right]4{\mathrm{s}}^{2}3{\mathrm{d}}^{10}4{\mathrm{p}}^6$

(c)

Interpretation Introduction

Interpretation:

The electronic configuration of a given atom and its most stable ion is to be written.

Concept introduction:

The electronic configuration is the arrangement of electrons in an atom. The atoms lose or gain electrons to acquire noble gas configuration because the ion which achievesthe nearest noble gas configuration is most stable.

Answer to Problem 20A

Electronic configuration of $\mathrm{C}\mathrm{s}$ according to Aufbau’s Principle is:

  $\left[\mathrm{X}\mathrm{e}\right]6{\mathrm{s}}^1$

Therefore, Electronic configuration of $\mathrm{C}{\mathrm{s}}^{+}$ :

  $\left[\mathrm{X}\mathrm{e}\right]$

It attains configuration as $\mathrm{X}\mathrm{e}$

Explanation of Solution

Cesium belongs to the first group. So it has a tendency to lose one electron and form the most stable ion $\mathrm{C}{\mathrm{s}}^{+}$ .

Electronic configuration of $\mathrm{C}\mathrm{s}$ according to Aufbau’s Principle is:

  $\left[\mathrm{X}\mathrm{e}\right]6{\mathrm{s}}^1$

Therefore, Electronic configuration of $\mathrm{C}{\mathrm{s}}^{+}$ :

  $\left[\mathrm{X}\mathrm{e}\right]$

(d)

Interpretation Introduction

Interpretation:

The electronic configuration of the given atom and its most stable ion is to be written.

Concept introduction:

The electronic configuration is the arrangement of electrons in an atom. The atoms lose or gain electrons to acquire noble gas configuration because the ion which achievesthe nearest noble gas configuration is most stable.

Answer to Problem 20A

Electronic configuration of $\mathrm{S}$ according to Aufbau’s Principle is:

  $\left[\mathrm{N}\mathrm{e}\right]3{\mathrm{s}}^{2}3{\mathrm{p}}^4$

Therefore, Electronic configuration of ${\mathrm{S}}^{2-}$ :

  $\left[\mathrm{N}\mathrm{e}\right]3{\mathrm{s}}^{2}3{\mathrm{p}}^6$

It attains configuration as $\mathrm{A}\mathrm{r}$

Explanation of Solution

Sulfur belongs to the 16^th group. So it has a tendency to gain two electrons and form the most stable ion ${\mathrm{S}}^{2-}$ .

Electronic configuration of $\mathrm{S}$ according to Aufbau’s Principle is:

  $\left[\mathrm{N}\mathrm{e}\right]3{\mathrm{s}}^{2}3{\mathrm{p}}^4$

Therefore, Electronic configuration of ${\mathrm{S}}^{2-}$ :

  $\left[\mathrm{N}\mathrm{e}\right]3{\mathrm{s}}^{2}3{\mathrm{p}}^6$

(e)

Interpretation Introduction

Interpretation:

The electronic configuration of the given atom and its most stable ion is to be written.

Concept introduction:

The electronic configuration is the arrangement of electrons in an atom. The atoms lose or gain electrons to acquire noble gas configuration because the ion which achievesthe nearest noble gas configuration is most stable.

Answer to Problem 20A

Electronic configuration of $\mathrm{M}\mathrm{g}$ according to Aufbau’s Principle is:

  $\left[\mathrm{N}\mathrm{e}\right]3{\mathrm{s}}^2$

Therefore, Electronic configuration of $\mathrm{M}{\mathrm{g}}^{2+}$ :

  $\left[\mathrm{N}\mathrm{e}\right]$

It attains configuration as $\mathrm{N}\mathrm{e}$

Explanation of Solution

Magnesium belongs to the 2^nd group. So it has a tendency to lose two electrons and form the most stable ion $\mathrm{M}{\mathrm{g}}^{2+}$ .

Electronic configuration of $\mathrm{M}\mathrm{g}$ according to Aufbau’s Principle is:

  $\left[\mathrm{N}\mathrm{e}\right]3{\mathrm{s}}^2$

Therefore, Electronic configuration of $\mathrm{M}{\mathrm{g}}^{2+}$ :

  $\left[\mathrm{N}\mathrm{e}\right]$