Chapter 7, Problem 13QRT

(a)

Interpretation Introduction

Interpretation:

The Lewis electron dot structure for $Be{H}_2$ should be drawn and the molecular shape of the molecule has to be given.

Concept Introduction:

• Lewis structures are diagrams that represent the chemical bonding of covalently bonded molecules and coordination compounds.
• It is also known as Lewis dot structures which represent the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule.
• The Lewis structure is based on the concept of the octet rule so that the electrons shared in each atom should have 8 electrons in its outer shell.

Lewis structure for any molecule is drawn by using the following steps,

First the skeletal structure for the given molecule is drawn then the total number of valence electrons for all atoms present in the molecule is determined.

The next step is to subtract the electrons present in the total number of bonds present in the skeletal structure of the molecule with the total valence electrons such that considering each bond contains two electrons with it.

Finally, the electrons which got after subtractions have to be equally distributed such that each atom contains eight electrons in its valence shell.

Explanation of Solution

Given molecule is $Be{H}_2$.

The Lewis electron dot structure for given molecule can be determined by first drawing the skeletal structure. Then, the total number of valence electrons for all atoms present in the molecule is determined.

The next step is to subtract the electrons present in the total number of bonds present in the skeletal structure of the molecule with the total valence electrons such that considering each bond contains two electrons with it.

Finally, the electrons which got after subtractions have to be equally distributed considering each atom contains eight electrons in its valence shell.

Total number of valence electrons is given below:

  $\left(2\times 1\right)+\left(1\times 2\right)=4$

Therefore, the Lewis structure is given below:

The molecular geometry will be linear because of the presence of two bond pairs around the central atom.

The molecule is a ${\text{AX}}_2$ type of molecule and it has a linear geometry.

(b)

Interpretation Introduction

Interpretation:

The Lewis electron dot structure for $C{H}_{2}C{l}_2$ should be drawn and the molecular shape of the molecule has to be given.

Concept Introduction:

Refer to (a)

Explanation of Solution

Given molecule is $C{H}_{2}C{l}_2$.

The Lewis electron dot structure for given molecule can be determined by first drawing the skeletal structure. Then, the total number of valence electrons for all atoms present in the molecule is determined.

The next step is to subtract the electrons present in the total number of bonds present in the skeletal structure of the molecule with the total valence electrons such that considering each bond contains two electrons with it.

Finally, the electrons which got after subtractions have to be equally distributed considering each atom contains eight electrons in its valence shell.

Total number of valence electrons is given below:

  $\left(2\times 7\right)+\left(4\times 1\right)+\left(2\times 1\right)=20$

Total number of electrons in bonds present is given below:

  $\left(2\times 4\right)=8$.

The twelve electrons remaining will be distributing among chlorine atoms.

Therefore, the Lewis structure is given below:

The molecular geometry will be tetrahedral because of the presence of four bond pairs.

The central atom is surrounded with four bond pairs and is a ${\text{AX}}_4{\text{E}}_0$ type of molecule and it has a tetrahedral geometry.

(c)

Interpretation Introduction

Interpretation:

The Lewis electron dot structure for $B{H}_3$ should be drawn and the molecular shape of the molecule has to be given.

Concept Introduction:

Refer to (a)

Explanation of Solution

Given molecule is $B{H}_3$.

The Lewis electron dot structure for given molecule can be determined by first drawing the skeletal structure. Then, the total number of valence electrons for all atoms present in the molecule is determined.

The next step is to subtract the electrons present in the total number of bonds present in the skeletal structure of the molecule with the total valence electrons such that considering each bond contains two electrons with it.

Finally, the electrons which got after subtractions have to be equally distributed considering each atom contains eight electrons in its valence shell.

Total number of valence electrons is given below:

  $\left(1\times 3\right)+\left(3\times 1\right)=6$

Total number of electrons in bonds present is given below:

  $\left(2\times 3\right)=6$.

Therefore, the Lewis structure is given below:

The molecular geometry will be triangular planar because of the presence of three bond pairs.

The central atom is surrounded with three bond pairs and is a ${\text{AX}}_3{\text{E}}_0$ type of molecule and it has a triangular planar geometry.

(d)

Interpretation Introduction

Interpretation:

The Lewis electron dot structure for $SeC{l}_6$ should be drawn and the molecular shape of the molecule has to be given.

Concept Introduction:

Refer to (a)

Explanation of Solution

Given molecule is $SeC{l}_6$.

The Lewis electron dot structure for given molecule can be determined by first drawing the skeletal structure. Then, the total number of valence electrons for all atoms present in the molecule is determined.

The next step is to subtract the electrons present in the total number of bonds present in the skeletal structure of the molecule with the total valence electrons such that considering each bond contains two electrons with it.

Finally, the electrons which got after subtractions have to be equally distributed considering each atom contains eight electrons in its valence shell.

Total number of valence electrons is given below:

  $\left(7\times 6\right)+\left(6\times 1\right)=48$

Total number of electrons in bonds present is given below:

  $\left(2\times 6\right)=12$.

The thirty-six electrons remaining will be distributing among oxygen atoms.

Therefore, the Lewis structure is given below:

The molecular geometry will be octahedral because of the presence of six bond pairs.

The central atom is surrounded with six bond pairs and is a ${\text{AX}}_6{\text{E}}_0$ type of molecule and it has a triangular planar geometry.

(e)

Interpretation Introduction

Interpretation:

The Lewis electron dot structure for $P{F}_3$ should be drawn and the molecular shape of the molecule has to be given.

Concept Introduction:

Refer to (a)

Explanation of Solution

Given molecule is $P{F}_3$.

The Lewis electron dot structure for given molecule can be determined by first drawing the skeletal structure. Then, the total number of valence electrons for all atoms present in the molecule is determined.

The next step is to subtract the electrons present in the total number of bonds present in the skeletal structure of the molecule with the total valence electrons such that considering each bond contains two electrons with it.

Finally, the electrons which got after subtractions have to be equally distributed considering each atom contains eight electrons in its valence shell.

Total number of valence electrons is given below:

  $\left(3\times 7\right)+\left(5\times 1\right)=26$

Total number of electrons in bonds present is given below:

  $\left(2\times 3\right)=6$.

The twenty electrons remaining will be distributing among oxygen atoms.

Therefore, the Lewis structure is given below:

The molecular geometry will be triangular pyramidal because of the presence of three bond pair and one lone pair of electron.