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The Behavioural model (e.g., acids are ‘sharp’) – from antiquity.
The Lavoisier model (acids as containing oxygen) – 1777.
The Priestley model (acids as containing hydrogen) – 1777.
The Arrhenius model (acids produce hydrogen ions in solution) – 1884.
The Bronsted–Lowry model (acids as proton donors) – 1923.
The Lewis model (acids as lone-pair acceptors) – 1923.
The Usanovitch model (general solvent model) – 1939.