Chapter 4, Problem 4.25UKC

What is the geometry around the central atom in the following molecular models? (There are no “hidden” atoms: all atoms in each model are visible.)

Interpretation Introduction

Interpretation:

The geometry around the central atom in the given molecular model is to be determined.

Concept introduction:

Molecular shape can be predicted from the Lewis structure by using the valence-shell Electron-pair repulsion (VSEPR) model.

- Count the number of valence electron pairs (bond pairs and lone pairs).

- Assume that the valence electron pairs form a structure that allows them to be as far away from each other as possible.

- If there are only two bond pair electrons, the molecule is linear.

- If there are three bond pair electrons, the molecule is shaped like a trigonal planar.

- If there are four bond pair electrons, the molecule is shaped as a regular tetrahedral.

- Repulsion between lone pair-bond pair of electrons effect the geometry of molecules.

Bond angle is the angle between two bonds of a molecule and it is determined based on the geometry.

[Bond angles: $pyramidal<{\text{120}}^{\text{o}}$, $trigonalplanar={\text{120}}^{\text{o}}$, $tetrahidral={109.5}^{\circ }$]

Answer to Problem 4.25UKC

The geometry around the central atom in the given molecular model is tetrahedral.

Explanation of Solution

In the given molecular model,

Four atoms are bonded to the central atom.  The angle around the central atom is around ${109.5}^{\circ }$.

Therefore,

The geometry of the given molecular model is tetrahedral.

Interpretation Introduction

Interpretation:

The geometry around the central atom in the given molecular model is to be determined.

Concept introduction:

Molecular shape can be predicted from the Lewis structure by using the valence-shell Electron-pair repulsion (VSEPR) model.

- Count the number of valence electron pairs (bond pairs and lone pairs).

- Assume that the valence electron pairs form a structure that allows them to be as far away from each other as possible.

- If there are only two bond pair electrons, the molecule is linear.

- If there are three bond pair electrons, the molecule is shaped like a trigonal planar.

- If there are four bond pair electrons, the molecule is shaped as a regular tetrahedral.

- Repulsion between lone pair-bond pair of electrons effect the geometry of molecules.

Bond angle is the angle between two bonds of a molecule and it is determined based on the geometry.

[Bond angles: $pyramidal<{\text{120}}^{\text{o}}$, $trigonalplanar={\text{120}}^{\text{o}}$, $tetrahidral={109.5}^{\circ }$]

Answer to Problem 4.25UKC

The geometry around the central atom in the given molecular model is pyramidal.

Explanation of Solution

In the given molecular model,

Three atoms are bonded to the central atom. Three atoms are bonded to the central atom. The angle around the central atom is around $<{120}^{\circ }$.

Therefore,

The geometry of the given molecular model is pyramidal.

Interpretation Introduction

Interpretation:

The geometry around the central atom in the given molecular model is to be determined.

Concept introduction:

Molecular shape can be predicted from the Lewis structure by using the valence-shell Electron-pair repulsion (VSEPR) model.

- Count the number of valence electron pairs (bond pairs and lone pairs).

- Assume that the valence electron pairs form a structure that allows them to be as far away from each other as possible.

- If there are only two bond pair electrons, the molecule is linear.

- If there are three bond pair electrons, the molecule is shaped like trigonal planar.

- If there are four bond pair electrons, the molecule is shaped as a regular tetrahedral.

- Repulsion between lone pair-bond pair of electrons effect the geometry of molecules.

Bond angle is the angle between two bonds of a molecule and it is determined based on the geometry.

[Bond angles: $pyramidal<{\text{120}}^{\text{o}}$, $trigonalplanar={\text{120}}^{\text{o}}$, $tetrahidral={109.5}^{\circ }$]

Answer to Problem 4.25UKC

The geometry around the central atom in the given molecular model is trigonal planar.

Explanation of Solution

In the given molecular model,

Three atoms are bonded to the central atom. The angle around the central atom is around ${120}^{\circ }$.

Therefore,

The geometry of the given molecular model is trigonal planar.