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Alchemy is disproved
Robert Boyle publishes The Skeptical Chemist and Aristotle's four-elements theory is disproved, leading to the "Death of Alchemy". -
Dalton's Atomic theory is published
John Dalton publishes his Atomic Theory stating that all matter is composed of small, indivisible atoms. -
First vacuum tube is invented
Heinrich Geissler invents the first vacuum tube. It is used in chemistry to demonstrate the movement of electrons. -
Goldstein discovers the proton
Eugene Goldstein discovers positive particles, or protons, by using a tube filled with hydrogen gas. -
Thomson places Crooke's tube within a magnetic field
J.J. Thomson concludes that all atoms have negative charge and renames cathode rays electrons. He creates a model in which the atom shows a positively charged sphere with negatively charged electrons sticking to it. -
Mass of an electron is discovered
Robert Millikan discovered the mass of an electron by introducing charged oil droplets into an electrically charged field. -
Rutherford creates new atomic model
Rutherford's model shows an atom containing a large amount of empty space, with a tiny dense positively charged nucleus surrounded by electrons traveling at extremely high speeds. -
Bohr model is published
Niels Bohr publishes what becomes known as the Bohr model, the theory that electrons travel in discrete orbits around the atom's nucleus. -
Chadwick discovers the neutron
At Cambridge University, James Chadwick discovers the neutron, which will become crucial to the fission of uranium-235.
