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The Evolution of the Atomic Theory


 150 years ago John Dalton formulated the idea that the world around us is made up of large numbers of identical very small particles called molecules, and that the many types of different kinds of molecules are simply differently arranged groups of atoms. It is this idea of the molecule that lies at the heart of chemistry.

The relative masses of compounds and elements were studied extensively in the 18th  century. John Dalton recognized a pattern in collected measurements and created a set of empirical laws which we now call the atomic theory of matter.

The understanding of the nature of matter as molecules was first set down by John Dalton . In the course of his studies and teaching he developed the ideas which led to his formulation of the atomic theory of matter in 1805.

Quantitative chemical measurements had lead to several empirical laws. Dalton was the first to come up with a theory that attempted to explain the empirical laws. It was to explain these empirical laws that he developed the atomic theory of matter.

Dalton determines that each element corresponds to a unique atom and he develops a system of chemical symbols based on atomic mass.

He says that compounds are atoms linked as molecules and this way of thinking opens the way for new laws of physics.


The empirical law of multiple proportions was developed by Dalton himself around 1804.

Chemirty 11 project The Evolution of the Atomic Theory