Dalton publishes his atomic theory
- Date
- 1808
- Category
- Science, technology & invention
- Region
- Britain (Manchester)
- Era
- Modern
- Significance
In the first part of A New System of Chemical Philosophy (1808), the English chemist and meteorologist John Dalton set out a coherent atomic theory of matter, building on ideas he had been developing since around 1803.
Dalton proposed that each chemical element consists of identical, indivisible atoms of a characteristic weight, that compounds form when atoms combine in fixed whole-number ratios, and that chemical reactions merely rearrange atoms rather than creating or destroying them. To make the theory quantitative he compiled the first table of relative atomic weights and devised a system of symbols for the elements. By grounding chemistry in the measurable masses of discrete particles, Dalton transformed it from a largely qualitative pursuit into a rigorous quantitative science and explained empirical regularities such as the law of multiple proportions. Although the existence of atoms remained contested for much of the nineteenth century, Dalton's framework underpinned the development of chemical formulae, stoichiometry, and ultimately the periodic system. It remains a foundation of modern chemistry and physics.
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Empires active in 1808
- Russian Empire1721 CE – 1917 CE
- British Empire1583 CE – 1997 CE
- Qing Dynasty1636 CE – 1912 CE
- Spanish Empire1492 CE – 1976 CE
- Portuguese Empire1415 CE – 1999 CE
- Mughal Empire1526 CE – 1857 CE
Related science, technology & invention events
- Opening of the Stockton and Darlington Railway27 September 1825
- Faraday discovers electromagnetic induction29 August 1831
- Third Plague Pandemic begins in Yunnan1855 (origin in Yunnan); global spread from 1894
- Darwin publishes On the Origin of Species24 November 1859
- Maxwell formulates the theory of electromagnetism1865–1873
- Opening of the Suez Canal17 November 1869
Further reading
The wider story
A Little History of Science
Warm, jargon-free tour of discovery from Babylonian stargazers to the genome.
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