SAT Subject Test Chemistry

PART 2

REVIEW OF MAJOR TOPICS

CHAPTER 3

Bonding

RESONANCE STRUCTURES

It is not always possible to represent the bonding structure of a molecule by either the Lewis dot structure or the line drawing because data about the bonding distance and bond strength are between possible drawing configurations and really indicate a hybrid condition. To represent this situation, the possible alternatives are drawn with arrows between them. Classic examples are sulfur trioxide and benzene. These structures are shown in Chapters 13 and 14, respectively, but are repeated here as examples.

TIP 

Resonance structure is a hybrid of the possible drawings because no one Lewis structure can represent the situation.

Sulfur trioxide resonance structures:

Benzene resonance structures: