Chapter 8, Problem 8.98QP

(a)

Interpretation Introduction

Interpretation: The molecules in which phosphorus atom has an expanded valence shell is to be stated.

Concept introduction: Atomic number of phosphorus is greater than twelve, hence it can expand its octet due to presence of $\text{d}$ orbitals.

To determine: If phosphorus atom has an expanded valence shell in ${\text{POCl}}_3$.

Answer to Problem 8.98QP

Phosphorus has an expanded valence shell in ${\text{POCl}}_3$.

Explanation of Solution

Explanation

The atomic number of phosphorus is $15$.

The ground state electronic configuration of $\text{P}$ is ${\text{1s}}^{\text{2}},{\text{2s}}^{\text{2}},{\text{2p}}^{\text{6}},{\text{3s}}^{\text{2}},{\text{3p}}_{\text{x}}{}^1,{\text{3p}}_{\text{y}}{}^{\text{1}},{\text{3p}}_{\text{z}}{}^{\text{1}}$.

The excited state electronic configuration of $\text{P}$ is

${\text{1s}}^{\text{2}},{\text{2s}}^{\text{2}},{\text{2p}}^{\text{6}},{\text{3s}}^1,{\text{3p}}_{\text{x}}{}^1,{\text{3p}}_{\text{y}}{}^{\text{1}},{\text{3p}}_{\text{z}}{}^{\text{1}},3{\text{d}}_{\text{xy}}{}^{\text{1}}$.

The atomic number of oxygen is $8$.

The ground state electronic configuration of $\text{O}$ is ${\text{1s}}^{\text{2}},{\text{2s}}^{\text{2}},{\text{2p}}_{\text{x}}{}^2,{\text{2p}}_{\text{y}}{}^1,{\text{2p}}_{\text{z}}{}^1$.

The atomic number of chlorine is $17$.

The ground state electronic configuration of $\text{Cl}$ is ${\text{1s}}^{\text{2}},{\text{2s}}^{\text{2}},{\text{2p}}^{\text{6}},{\text{3s}}^{\text{2}},{\text{3p}}_{\text{x}}{}^{\text{2}}{\text{,3p}}_{\text{y}}{}^{\text{2}}{\text{,3p}}_{\text{z}}{}^{\text{1}}$.

There are five unpaired electrons in excited state of phosphorus due to promotion of electron to available d orbital. The unpaired electrons in oxygen is $2$ and upaired electron in chlorine is $1$. There are $3$ chlorine atoms and $1$ oxygen atom in ${\text{POCl}}_3$. The three chlorine atoms and one oxygen atom will react with five unpaired electrons in phosphorus to form ${\text{POCl}}_3$. Due to presence of d orbital, phosphorus will expand its valence shell and form ${\text{POCl}}_3$.

(b)

Interpretation Introduction

To determine: If phosphorus atom has an expanded valence shell in ${\text{PF}}_{\text{5}}$.

Answer to Problem 8.98QP

Phosphorus has an expanded valence shell in ${\text{PF}}_{\text{5}}$.

Explanation of Solution

Explanation

The atomic number of phosphorus is $15$.

The ground state electronic configuration of $\text{P}$ is ${\text{1s}}^{\text{2}},{\text{2s}}^{\text{2}},{\text{2p}}^{\text{6}},{\text{3s}}^{\text{2}},{\text{3p}}_{\text{x}}{}^1,{\text{3p}}_{\text{y}}{}^{\text{1}},{\text{3p}}_{\text{z}}{}^{\text{1}}$.

The excited state electronic configuration of $\text{P}$ is

${\text{1s}}^{\text{2}},{\text{2s}}^{\text{2}},{\text{2p}}^{\text{6}},{\text{3s}}^1,{\text{3p}}_{\text{x}}{}^1,{\text{3p}}_{\text{y}}{}^{\text{1}},{\text{3p}}_{\text{z}}{}^{\text{1}},3{\text{d}}_{\text{xy}}{}^{\text{1}}$.

The atomic number of flourine is $9$.

The ground state electronic configuration of $\text{F}$ is ${\text{1s}}^{\text{2}},{\text{2s}}^{\text{2}},2{\text{p}}_{\text{x}}{}^{\text{2}}{\text{,2p}}_{\text{y}}{}^{\text{2}}{\text{,2p}}_{\text{z}}{}^{\text{1}}$.

There are five unpaired electrons in excited state of phosphorus due to promotion of electron to available d orbital. There are $5$ flourine atoms in ${\text{PF}}_{\text{5}}$. The five fluorine atoms will react with five unpaired electrons in phosphorus to form ${\text{PF}}_{\text{5}}$. Due to presence of d orbital, phosphorus will expand its valence shell and form ${\text{PF}}_{\text{5}}$.

(c)

Interpretation Introduction

To determine: If phosphorus atom has an expanded valence shell in ${\text{PF}}_3$.

Answer to Problem 8.98QP

Phosphorus does not have an expanded valence shell in ${\text{PF}}_3$.

Explanation of Solution

Explanation

The atomic number of phosphorus is $15$.

The ground state electronic configuration of $\text{P}$ is ${\text{1s}}^{\text{2}},{\text{2s}}^{\text{2}},{\text{2p}}^{\text{6}},{\text{3s}}^{\text{2}},{\text{3p}}_{\text{x}}{}^1,{\text{3p}}_{\text{y}}{}^{\text{1}},{\text{3p}}_{\text{z}}{}^{\text{1}}$.

The atomic number of flourine is $9$.

The ground state electronic configuration of $\text{F}$ is ${\text{1s}}^{\text{2}},{\text{2s}}^{\text{2}},2{\text{p}}_{\text{x}}{}^{\text{2}}{\text{,2p}}_{\text{y}}{}^{\text{2}}{\text{,2p}}_{\text{z}}{}^{\text{1}}$.

There are three unpaired electrons in ground state of phosphorus. There are $3$ flourine atoms in ${\text{PF}}_3$. The three fluorine atoms will react with three unpaired electrons in phosphorus to form ${\text{PF}}_3$. Since d orbitals are not used, phosphorus does not have an expanded valence shell in ${\text{PF}}_3$.

(d)

Interpretation Introduction

To determine: If phosphorus atom has an expanded valence shell in ${\text{P}}_2{\text{F}}_4$.

Answer to Problem 8.98QP

Phosphorus does not have an expanded valence shell in ${\text{P}}_2{\text{F}}_4$.

Explanation of Solution

Explanation

The atomic number of phosphorus is $15$.

The ground state electronic configuration of $\text{P}$ is ${\text{1s}}^{\text{2}},{\text{2s}}^{\text{2}},{\text{2p}}^{\text{6}},{\text{3s}}^{\text{2}},{\text{3p}}_{\text{x}}{}^1,{\text{3p}}_{\text{y}}{}^{\text{1}},{\text{3p}}_{\text{z}}{}^{\text{1}}$.

The atomic number of flourine is $9$.

The ground state electronic configuration of $\text{F}$ is ${\text{1s}}^{\text{2}},{\text{2s}}^{\text{2}},2{\text{p}}_{\text{x}}{}^{\text{2}}{\text{,2p}}_{\text{y}}{}^{\text{2}}{\text{,2p}}_{\text{z}}{}^{\text{1}}$.

There are three unpaired electrons in ground state of phosphorus. Fluorine has one unpaired electron in its valence orbital. The two fluorine atoms will react with two unpaired electrons that are located at the ${\text{3p}}_{\text{x}}$ and ${\text{3p}}_{\text{y}}$ orbitals while the ${\text{3p}}_{\text{z}}$ orbital is paired with unpaired electron of the second phosphorus atom. Similarly, the second phosphorus atom will react with two phosphorus atom and the third electron will pair up with the first phosphorus atom and form ${\text{P}}_2{\text{F}}_4$ molecule. Since d orbitals are not used, phosphorus does not have an expanded valence shell in ${\text{P}}_2{\text{F}}_4$.