OrgoChem I

Resonance & Acid-Base

Drawing resonance forms, Brønsted-Lowry, pKa, conjugate pairs, equilibrium direction

Summary

Master resonance (π bonds and lone pairs move; σ bonds stay) and acid-base (equilibrium favors weaker acid). Essential foundation for all of orgo.

What you need to know:

This topic covers resonance & acid-base. Focus on mastering the key concepts in the "Must know checklist" below. Follow the study steps systematically, and use practice problems to reinforce your understanding. The external reference provides comprehensive coverage of all concepts.

Video Tutorial

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Resonance Structures - How To Draw The Resonance Hybrid

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Must know checklist

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Resonanceπ bonds and lone pairs can move; σ bonds and atom positions stay fixed; resonance forms differ only in electron placement
Resonance Structures - Drawing Resonance Hybrid→
Charge formulaformal charge = valence − bonds − lone pairs; use to check resonance structures
Acid-Base Reactions and pKa→
Brønsted-Lowryacid = proton donor; base = proton acceptor; conjugate acid = base + H⁺; conjugate base = acid − H⁺
Conjugate Acid-Base Pairs→
Equilibrium favors weaker acid (higher pKa); lower pKa = stronger acid; conjugates are on the side of the weaker acid
Predicting Equilibrium from pKa→
Predicting reactionslabel acid, base, conjugate acid, conjugate base; compare pKa; equilibrium arrows point toward weaker acid
pKa Values and Acid Strength→

Common mistakes

Moving σ bonds in resonance (only π and lone pairs move)

Forgetting conjugate pairs are on the same side of equilibrium

Equilibrium favors stronger acid (wrong—favors weaker acid, higher pKa)

Not labeling all four: acid, base, conjugate acid, conjugate base