Chapter 7, Problem ISP

Write the Lewis structures and give the electron-region geometry, molecular geometry, and bond angles, and the hybridization of the central atom of these polyatomic ions and molecules.

1. (a) ${\text{BrF}}_2^{+}$
2. (b) OCCl₂
3. (c) ${\text{CH}}_3^{+}$
4. (d) SeCS
5. (e) ${\text{CH}}_3^{-}$

Interpretation Introduction

Interpretation:

Lewis structure, electron-region geometry, molecular-geometry, bond angle and hybridization of the central atom in ${\text{BrF}}_{\text{2}}^{\text{+}}$ have to be described.

Concept Introduction:

Lewis structures are diagrams that represent the chemical bonding of covalently bonded molecules and coordination compounds.

Electron geometry is the shape of a molecule predicted by considering both bond electron pairs and lone pair of electrons.

Molecular geometry is the shape of a molecule predicted by considering only bond pair of electrons

Geometry of different type of molecules with respect to the number of electron pairs are mentioned below,

$\begin{array}{ccccc}\begin{array}{l}Typeof\\ Molecule\end{array}& \begin{array}{l}No.ofatoms\\ bondedtocentralatoms\end{array}& \begin{array}{l}No.oflonepairs\\ oncentralatom\end{array}& \begin{array}{l}Arrangementof\\ electronpairs\end{array}& \begin{array}{l}Molecular\\ Geometry\end{array}\\ A{B}_2& 2& 0& Linear& Linear\\ A{B}_3& 3& 0& Trigonalplanar& Trigonalplanar\\ A{B}_4& 4& 0& Tetrahedral& Tetrahedral\\ A{B}_5& 5& 0& Trigonalbipyramidal& Trigonalbipyramidal\\ A{B}_6& 6& 0& Octahedral& Octahedral\end{array}$

Explanation of Solution

Given molecule is ${\text{BrF}}_{\text{2}}^{\text{+}}$

The Lewis electron dot structure is given below:

  .

The molecular geometry will be angular because of the presence of two bond pairs and two lone pair around the central atom.

There will be four electron regions in the molecule and it is a type of ${\text{AX}}_2{\text{E}}_2$ molecule.

The electron-region geometry will be tetrahedral.

The hybridization will be ${\text{sp}}^{\text{3}}$ around bromine atom and the bond angle of the molecule will be slightly less than $109.5°$.

Interpretation Introduction

Interpretation:

Lewis structure, electron-region geometry, molecular-geometry, bond angle and hybridization of the central atom in ${\text{OCCl}}_2$ have to be described.

Concept Introduction:

Refer to (a).

Explanation of Solution

Given molecule is ${\text{OCCl}}_2$.

The Lewis electron dot structure is given below:

  .

The molecular geometry will be trigonal planar because of the presence of three bond pairs around the central atom.

There will be three electron regions in the molecule and it is a type of ${\text{AX}}_3{\text{E}}_0$ molecule.

The electron-region geometry will be triangular planar.

The hybridization will be ${\text{sp}}^2$ around carbon atom and the bond angle of the molecule will be $120°$.

Interpretation Introduction

Interpretation:

Lewis structure, electron-region geometry, molecular-geometry, bond angle and hybridization of the central atom in ${\text{CH}}_3^{\text{+}}$ have to be described.

Concept Introduction:

Refer to (a).

Explanation of Solution

Given molecule is ${\text{CH}}_3^{\text{+}}$.

The Lewis electron dot structure is given below:

  .

The molecular geometry will be trigonal planar because of the presence of three bond pairs around the central atom.

There will be three electron regions in the molecule and it is a type of ${\text{AX}}_3{\text{E}}_0$ molecule.

The electron-region geometry will be triangular planar.

The hybridization will be ${\text{sp}}^2$ around carbon atom and the bond angle of the molecule will be $120°$.

Interpretation Introduction

Interpretation:

Lewis structure, electron-region geometry, molecular-geometry, bond angle and hybridization of the central atom in $\text{SeCS}$ have to be described.

Concept Introduction:

Refer to (a).

Explanation of Solution

Given molecule is $\text{SeCS}$

The Lewis electron dot structure is given below:

  .

The molecular geometry and angular geometry will be linear because of the presence of two bond pairs around the central atom it is a type of ${\text{AX}}_2{\text{E}}_0$ molecule.

The hybridization will be $\text{sp}$ around carbon atom and the bond angle of the molecule is $180°$.

Interpretation Introduction

Interpretation:

Lewis structure, electron-region geometry, molecular-geometry, bond angle and hybridization of the central atom in ${\text{CH}}_{\text{3}}^{\text{-}}$ have to be described.

Concept Introduction:

Refer to (a).

Explanation of Solution

Given molecule is ${\text{CH}}_{\text{3}}^{\text{-}}$.

The Lewis electron dot structure is given below:

  .

The molecular geometry will be trigonal pyramidal because of the presence of three bond pairs and one lone pair around the central atom.

There will be four electron regions in the molecule and it is a type of ${\text{AX}}_3{\text{E}}_1$ molecule.

The electron-region geometry will be tetrahedral.

The hybridization will be ${\text{sp}}^{\text{3}}$ around carbon atom and the bond angle of the molecule will be slightly less than $109.5°$.