Sometime compounds have the potential to have more than one Lewis Dot Structures. These equivalent structures are called Resonance Structures.
When do you have Resonance Structures?
The following two conditions must be met:
If these conditions are met, you have resonance structures. As you will see in the following example, you are really asking the quesiton,
Why can't the different bond (e.g. a double bond when all other bonds are single) be on another one of the outside atoms?
IF YOU HAVE RESONANCE, YOU MUST SHOW ALL RESONANCE STRUCTURES FOR THE ANSWER TO BE CORRECT.
Homework: Read this website,[Example of resonance structure], and write down (in your notes) the resonance structures for O3.