Historical Background - Romantic (1820-1900 AD)
1826 AD Berzelius proposes new system of symbolic notation.
1831 Faraday discovers electromagnetic induction and devises the first electrical generator.  Begins work on electrolysis.
1832 Faraday introduces the terms electrode, anode, cathode, ion.
1833 Faraday announces the laws of electrolysis.
At a meeting of the British Association for the Advancement of Science, William Whewell proposes the term ‘scientist.’
1838 Charles Goodyear invents vulcanized rubber.
1846 In a short paper “Thoughts on Ray Vibrations,” Faraday discusses the possibility of doing away with the 'aether'.
1847 Hermann Helmholtz proposes the law of the conservation of energy (the first law of thermodynamics).
1848 William Thomson (later Lord Kelvin) calculates the absolute zero point of temperature.
1852 Faraday publishes “On the Physical Character of the Lines of Magnetic Force,” charging that Newtonian science is an obstacle to the progress of science.
Edward Frankland, first paper on organo-metallics and first mention of the theory of valency.
1858 Friedrich Kekulé publishes his paper on bonding in carbon compounds.
Stanislas Cannizzaro resurrects Avogadro’s hypothesis.
1860 Marcellin Berthelot synthesizes new organic molecules (methane, ethyl alcohol, methyl alcohol) from the elements, adding another blow to vitalist theories.
First meeting of the International Chemical Congress at Karlsruhe.
1865 Friedrich August Kekulé proposes a ring structure for benzene, reportedly after dreaming about six monkeys holding one another by the tail.
Clausius coins the term “entropy” and states the first two laws of thermodynamics as “the energy of the universe is constant” and “the entropy of the universe tends to a maximum.”
1866 Leclanché invents the electrical battery (dry cell).
1869 Dmitri Mendeleev proposes his periodic table of the elements, predicting the existence of three new elements (gallium, scandium, and germanium).
1871 Eugen Goldstein submits that cathode radiation sustains a wave interpretation of matter.
Cromwell Varley submits that cathode radiation sustains a particulate theory.
1874 Kelvin formally states the second law of thermodynamics.
Joseph Achille Le Bel and Jacobus van’t Hoff  independently propose that the molecule has a three-dimensional structure (stereochemistry). 
1875 In a zinc ore mined in the Pyrenees, Lecoq de Boisbaudran discovers gallium, in support of Mendeleev.
Winkler discovers germanium, in support of Mendeleev.
Crookes claims that cathode radiation points to a fourth state of matter that is particulate in nature. 
1876 Julius Plücker describes the phenomenon of cathode rays and is the first to use the term.
1879 Nilson discovers scandium, in support of Mendeleev.
1887 Foundation by Friedrich Ostwald of the Zuitschrift für physikalische Chemie, marking establishment of the discipline of physical chemistry.
1888 Hertz demonstrates propagation of electromagnetic waves (radio waves).
1891 George Johnstone Stoney suggests the term ‘electron’ for unit of electricty.
1892 (to 1904) Konrad Lorenz develops his electron theory.
1895 William Ramsay and William Crookes identify the element helium on Earth.
Wilhelm Wilhelm Conrad Röntgen discovers X-rays which were immediately used to visualize bodily structures.
1896 Antoine Henri Becquerel discovers natural radioactivity in uranium salts. 
1897 JJ Thomson shows that electrons are independent particles.
1898 Marie and Pierre Curie isolate the radioactive elements of radium and polonium
John Sealy Townsend measures the charge of an electron.
1899 Alpha and beta rays shown by Ernest Rutherford to be distinct types of radiation.
Rutherford notices thorium emanation.
Paul-Ulrich Villard observes gamma rays.