19th Century- Swedish chemist Arrhenius put forward ideas about acids and bases.
Suggested when acids and bases dissolve in water they seperate partially or completely into charged ion (dissociation)
Said that acids dissociate in water to produce hydrogen ions (H+), e.g. HCL -> H+ + Cl-
According to Arrhenius, all differences seen between acids with different formulae were due to the hydrogen ions they produce when dissovled in water.
Also said that bases all produce hydroxide ions (OH-) when in solution.
Hisi deas took a long time to be accepted as a) not everyone…