Timeline

15 moments that made chemistry what it is. Each one is a publication, a first or a decision that can be looked up.

1. 1661Robert Boyle’s The Sceptical Chymist argues that elements should be established by experiment, not inherited from Aristotle.
2. 1774Joseph Priestley isolates oxygen; Carl Wilhelm Scheele had done so independently a few years earlier.
3. 1789Antoine Lavoisier’s Traité élémentaire de chimie states the conservation of mass and spreads the new chemical names that he and three colleagues had proposed in 1787.
4. 1808John Dalton publishes his atomic theory.
5. 1811Amedeo Avogadro proposes that equal volumes of gases contain equal numbers of molecules.
6. 1828Friedrich Wöhler makes urea from inorganic starting materials, blurring the line between living and non-living chemistry.
7. 1869Dmitri Mendeleev publishes the periodic table.
8. 1897J. J. Thomson identifies the electron: atoms have parts.
9. 1913Henry Moseley orders the elements by atomic number; the Braggs determine crystal structures with X-rays; ammonia is made industrially by the Haber–Bosch process.
10. 1916Gilbert Lewis describes the covalent bond as a shared pair of electrons.
11. 1939Linus Pauling publishes The Nature of the Chemical Bond.
12. 1953The double-helix structure of DNA is published by Watson and Crick, drawing on Rosalind Franklin’s X-ray data.
13. 1985Kroto, Curl and Smalley discover the fullerenes, a new form of carbon.
14. 2016IUPAC approves the names nihonium, moscovium, tennessine and oganesson, completing the seventh row of the periodic table.
15. 2019The mole is redefined by fixing the Avogadro constant, cutting its link to a physical mass standard.