Chapter 1, Problem 50P

Interpretation Introduction

Interpretation:

The more stable structure of two possible structures for the conjugate acid of guanidine is to be identified, and resonance structures showing electron delocalization are to be drawn.

Concept introduction:

According to the resonance concept, Lewis formulas that have different distribution of electrons in their structure can be written for a single molecule. Lewis formulas that confer to a resonance hybrid can be made easier to understand by using curved arrows to represent the delocalized electrons.

Each structure contributing to resonance must have an equal total number of valence electrons and the same value of net charge. Among the various Lewis formulas written for a molecule, the formal charges on individual atoms may vary. Each structure contributing to resonance must have the same number of unshared electrons.

When two or more structures satisfy the octet rule, the major contributor structure is the one with the smallest separation of oppositely charged atoms. The contributor structure with the least number of formal charges is more stable.