Chapter 7, Problem 7.76PAE

7.68 Give approximate values for the indicated bond angles. (a) Cl—S—Cl in SCl₂, (b) N—N—O in N₂O, (c) bond angles marked as 1, 2, and 3 in the following structure for vinyl alcohol:

Interpretation Introduction

Interpretation:

The approximate value for the indicated bond angle of the following molecule should be determined:$\text{Cl}-\text{S}-\text{Cl}$ in ${\text{SCl}}_2$

Concept Introduction

A bond angleis the angle formed between three atoms across at least two bonds. We can predict the angle of a molecule by the knowledge of their bond pairs, lone pairs and VSPER theory.According to this theory, the atoms take such a position in which there is a minimum possible repulsion between the bonded atoms and the lone pair of electrons, if any, where the lone pair is the pair of electrons occupying the orbital but not taking part in the bonding.

The main concept behind this theory is that the electron pairs are always present in the outermost shell i.e. valence shell of an atom of a molecule and they repel each other due to which they try to attain the best possible position so that the value of their repulsion is the least. Hence, the electrons occupy such positions around the atom that reduces their repulsion and provides a shape to their molecule.

Here, the electrons that take part in the bonding of a molecule are known as the bonding pair and the electrons that do not take part in the bonding are known as the lone pairs. The bond pairs are in the influence of the two bonding atoms whereas the lone pairs are in the influence of only of the atom.

Due to the presence of lone pairs there is more space occupied between the atoms of the molecules. The repulsion between the lone pair-lone pair and bond pair-lone pair changes the position of atom as well as bond angles. The order of repulsion is as follows:

$\text{lp}-\text{lp}>\text{lp}-\text{bp}>\text{bp}-\text{bp}$

It means the lone pair-lone pair repulsion is more than lone pair- bond pair repulsion and bond pair- bond pair repulsion is least among all.

Answer to Problem 7.76PAE

Solution:

The bond angle of $\text{Cl}-\text{S}-\text{Cl}$ in ${\text{SCl}}_2$ is ${103}^{\text{o}}$ having a bent shape rather than that of a tetrahedral.

Explanation of Solution

The electronic configuration of sulphur (S) is $3s^{2}3p^{4}3d^0$. In the excited state the configuration becomes $3s^{2}3p^{3}3d^2$. Thus, there is mixing of the s and p orbitals in the excited form to form four half-filled sp³ hybrid orbitals. These orbitals combine with chlorine to form their respective sigma bonds. The arrangement of the bond-pair and the lone-pair is such that each of them suffers the minimum repulsion. Hence, the shape is bent with the bond angle is less than ${109.5}^{\text{o}}$. Experimentally, the determined bond angle is ${103}^{\text{o}}$. Shape of ${\text{SCl}}_2$ is bent with the bond angle of ${103}^{\text{o}}$

Interpretation Introduction

Interpretation: The approximate value for the indicated bond angle of the following molecule should be determined:

$\text{N}-\text{N}-\text{O}$ in ${\text{N}}_2\text{O}$

Concept Introduction

A bond angle is the angle formed between three atoms across at least two bonds. We can predict the angle of a molecule by the knowledge of their bond pairs, lone pairs and VSPER theory. According to this theory, the atoms take such a position in which there is a minimum possible repulsion between the bonded atoms and the lone pair of electrons, if any, where the lone pair is the pair of electrons occupying the orbital but not taking part in the bonding.

The main concept behind this theory is that the electron pairs are always present in the outermost shell i.e. valence shell of an atom of a molecule and they repel each other due to which they try to attain the best possible position so that the value of their repulsion is the least. Hence, the electrons occupy such positions around the atom that reduces their repulsion and provides a shape to their molecule.

Here, the electrons that take part in the bonding of a molecule are known as the bonding pair and the electrons that do not take part in the bonding are known as the lone pairs. The bond pairs are in the influence of the two bonding atoms whereas the lone pairs are in the influence of only of the atom.

Due to the presence of lone pairs there is more space occupied between the atoms of the molecules. The repulsion between the lone pair-lone pair and bond pair-lone pair changes the position of atom as well as bond angles. The order of repulsion is as follows:

$\text{lp}-\text{lp}>\text{lp}-\text{bp}>\text{bp}-\text{bp}$

It means the lone pair-lone pair repulsion is more than lone pair- bond pair repulsion and bond pair- bond pair repulsion is least among all.

Answer to Problem 7.76PAE

Solution:

The bond angle of ${\text{N}}_2\text{O}$ is ${180}^{\text{o}}$ having a linear shape.

Explanation of Solution

The electronic configuration of N is $2s^{2}2p^3$. In the excited state the configuration becomes $2s^{1}2p^4$. Thus, there is mixing of the s and p orbitals in the excited form to form two half-filled sp hybrid orbitals. These orbitals combine with nitrogen and oxygen to form their respective sigma and pi bonds. The arrangement of the bond pair and lone pair is such that each of them suffers the minimum repulsion. Hence, the shape of ${\text{N}}_2\text{O}$ is linear with the bond angle of ${180}^{\text{o}}$

Structure of ${\text{N}}_2\text{O}$ is linear with the bond angle of ${180}^{\text{o}}$

Interpretation Introduction

Interpretation: The approximate value for the indicated bond angle of the following molecule should be determined:

Concept Introduction

A bond angle is the angle formed between three atoms across at least two bonds. We can predict the angle of a molecule by the knowledge of their bond pairs, lone pairs and VSPER theory. According to this theory, the atoms take such a position in which there is a minimum possible repulsion between the bonded atoms and the lone pair of electrons, if any, where the lone pair is the pair of electrons occupying the orbital but not taking part in the bonding.

The main concept behind this theory is that the electron pairs are always present in the outermost shell i.e. valence shell of an atom of a molecule and they repel each other due to which they try to attain the best possible position so that the value of their repulsion is the least. Hence, the electrons occupy such positions around the atom that reduces their repulsion and provides a shape to their molecule.

Here, the electrons that take part in the bonding of a molecule are known as the bonding pair and the electrons that do not take part in the bonding are known as the lone pairs. The bond pairs are in the influence of the two bonding atoms whereas the lone pairs are in the influence of only of the atom.

Due to the presence of lone pairs there is more space occupied between the atoms of the molecules. The repulsion between the lone pair-lone pair and bond pair-lone pair changes the position of atom as well as bond angles. The order of repulsion is as follows:

$\text{lp}-\text{lp}>\text{lp}-\text{bp}>\text{bp}-\text{bp}$

It means the lone pair-lone pair repulsion is more than lone pair- bond pair repulsion and bond pair- bond pair repulsion is least among all.

Answer to Problem 7.76PAE

Solution:

The bond angle of vinyl alcoholare listed as under according to the marking: 1. ${120}^{\text{o}}$

2. ${120}^{\text{o}}$

3. ${109}^{\text{o}}28\text{'}$

Explanation of Solution

In the first angle $\text{H}-\text{C}-\text{H}$ carbon is having 3 sigma and 1 pi bond and is sp² hybridised therefore its geometry is trigonal planar having an angle of ${120}^{\text{o}}$. In $\text{C}=\text{C}-\text{H}$, the carbon is having 2 sigma and 1 pi bond. Hence, the shape must be trigonal-planar.Similarly in $\text{C}=\text{C}-\text{H}$ the carbon is sp² hybridised making an angle of ${120}^{\text{o}}$ and in the last pair $\text{C}-\text{O}-\text{H}$ the geometry is tetrahedral, hence, the angle must be ${109}^{\text{o}}28\text{'}$

Structure of $\text{Vinyl alcohol}$is given as under:

The bond angles of vinyl alcohol for their respective bonds are as follows:

1. ${120}^{\text{o}}$

2. ${120}^{\text{o}}$

3. ${109}^{\text{o}}28\text{'}$