Law of Multiple ProportionsLavoisier’s Experiment

Charcoal

Oxides of Carbon

Carbonic Acid Carbonic Oxide

John Dalton•Elements Composed of indivisible atoms.•Atoms are alike for a given element.•Atoms for different elements differ in size, mass, etc.•Compounds are formed from two or more atoms of different elements.•Atoms combine is simple numerical ratios to form compounds.

Dalton’s Atomic Theory

Rule of Greatest SimplicityWhen atoms combine in only one ratio, "..it must be presumed to be a binary one,unless some cause appear to the contrary"

Dalton’s Atoms

Dalton’s Chemical Formulations

Carbon Dioxide

Carbon Monoxide

Nearly all the symbols suggested by Berzelius are in use today.

At first symbols were not very popular among chemists. As late as 1837, Daltoncomplained that “Berzelius’ symbols are horrifying; a young student in chemistrymight as well learn Hebrew as make himself acquainted with them. They appearlike a chaos of atoms .. to equally perplex the adept of Science, to discourage thelearner as well as to cloud the beauty of the Atomic Theory.”

Berzellius’ Use of Symbols to Represent Atoms

The Development of Modern ChemistryBy Aaron J. Ihde

Chlorides of Iron

Ferrous Chloride Ferric Chloride

Oxides of Hydrogen

Water Hydrogen Peroxide