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Timeline of Discoveries

1776: Discovery and isolation of methane gas


1825: Discovery and isolation of benzene


1855: Coining of the term ‘aromatic’ in a chemical context

  • By: August Wilhelm Hofmann
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1865: Proposal of the cyclic structure of benzene

  • By: Friedrich August Kekulé
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1874: Proposal of the tetrahedral carbon atom theory, explaining optical activity and 3D molecular structure

  • By: Jacobus Henricus van ‘t Hoff, Joseph Achille Le Bel
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1916: Development of the concept of covalent bonding (electron pair sharing); term ‘covalent bond’ coined in 1919

  • By: Gilbert N. Lewis (concept), Irving Langmuir (term)
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1916: Formulation of the octet rule

  • By: Gilbert N. Lewis, Walther Kossel
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1931: Development of Hückel’s Rule for aromaticity



See also: 03_Study_Guide