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Theories of Acids and Bases

Chapter summary

Theories of Acids and Bases, at a glance

Choose the definition that explains the reaction: aqueous ions, proton transfer or electron-pair donation.

A-Level 9476 (2026-2027)

Quick revision

Revisit the essentials, then return to an explanation when you need it.

Three useful questions
TheoryAsk
ArrheniusDoes it increase H+(aq) or OH-(aq)?
Bronsted-LowryWhich species donates a proton, and which accepts it?
LewisWhere is the donated electron pair, and which species accepts it?

A conjugate pair differs by one H+. Water can be acid or base depending on its partner. BF3 accepting a lone pair from NH3 shows why acid-base chemistry is broader than aqueous neutralisation.

Revisit an explanation

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