Chapter 12, Problem 39A

Interpretation Introduction

Interpretation:

The geometric structure of water is to be drawn and the bond angle is to be written.

Concept introduction:

Structure of molecule can be drawn using VSEPR theory. The total number of bonding and non-bonding pairs of electrons tells about the geometry of the molecule.

The valence electrons are the electrons present in outermost shell.

Answer to Problem 39A

Geometric structure is tetrahedral.

Four pairs of valence electrons are there on oxygen.

The approximate bond angle of $H-O-H$ is $104\text{'}28\text{'}\text{'}$

Explanation of Solution

Lewis structure of $H_{2}O$is:

  

Structure shows in $H_{2}O$ central atom oxygen has two bond pairs and two lone pairs. In total it has 4 pairs of electrons. Thus, its geometry is tetrahedral. But due to presence of lone pair of electrons its structure gets distorted and its shape is bent or V-shaped. It has four pairs of valence electrons.

A normal tetrahedral bond has bond angle of $109\text{'}28\text{'}\text{'}$ but due to presence of lone pairs bond angle is reduced to $104\text{'}28\text{'}\text{'}$

Conclusion

Thus, water has bent shape due to presence of lone pairs.