Chapter 20, Problem 3A

Interpretation Introduction

Interpretation: The meaning double bond with examples and draw the Lewis structure of those molecules is to be determined.

Concept introduction: A multiple bond is formed when the atoms forming the bond share more than two electrons.

Answer to Problem 3A

Double bond involves sharing two pairs of electrons.

Explanation of Solution

Carbon can bond to fewer than four elements by forming one or more multiple bonds. Recall that a multiple bond involves the sharing of more than two electrons. For example, a double bond is formed when atoms forming the bond shares four electrons.

Examples of double bond molecules are:

	Molecules	Structure	Lewis dot structure
1	Carbon dioxide, ${\text{CO}}_{\text{2}}$	$\text{O}=\text{C}=\text{O}$	$\underset{••}{\overset{••}{\text{O}}}=\text{C}=\underset{••}{\overset{••}{\text{O}}}$
2	Ethylene, ${\text{C}}_{\text{2}}{\text{H}}_{\text{4}}$	$\begin{array}{l}\text{H}\text{H}\\ \backslash /\\ \text{C}=\text{C}\\ /\backslash \\ \text{H}\text{H}\end{array}$	$\begin{array}{l}\text{H}\text{H}\\ \backslash /\\ \text{C}=\text{C}\\ /\backslash \\ \text{H}\text{H}\end{array}$

Conclusion

Lewis dot structure help in visualizing the valence electrons of atoms.