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Period: 350 to
Atomic Theory
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440
Leucippus and Democritus
Democritus and his counterpart, Leucippus, were the first to theorize that the world was composed of atoms that were particles which were invisible to the human eye yet existed nonetheless. -
Napoleon
Napoleon becomes Consul -
John Dalton
John Dalton proposed the Law of Multiple Proportions which led to the proposal of the Atomic Theory in this same year. He also created what is known as the “mole model” and came up with a system to represent atoms of different elements. -
Napoleon
Napoleon defeated in Russia -
J.J. Thomson
Thomson is famous for identifying the negatively charged elections in the cathode ray tube. He theorized that the electron was a component of all matter. He is also credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer. -
Cuba
Cuba occupied by U.S. and released -
William Thomson
Thomson proposed the first structural theory of the atom. In this theory, an atom was hypothesized to have a uniformly distributed positive electrical cloud, Electrons were inserted to produce a situation when the negative charges were at rest. -
Russia and Japan
Russia and
Japan at war -
Robert A. Millikan
Millikan was an American physicist who received great praise for his measurement of the charge on the electron along with his work on the photoelectric effect. -
Niels Henrik David Bohr
Bohr was a Nobel Prize winner in Physics. He was a physicist who made great contributions to the understanding and solving of the complex mysteries of the atomic structure and quantum mechanics. -
World War
World War One begins:
Germany invades Belgium -
Rutherford
Rutherford proposed that all of the positive charge and all of the mass of the atom occupied a small volume at the center of the atom and that most of the volume of the atom was empty space occupied by the electrons. -
Italy
Italy becomes fascist -
Heisenberg
John Dalton proposed the Law of Multiple Proportions which led to the proposal of the Atomic Theory in this same year. He also created what is known as the “mole model” and came up with a system to represent atoms of different elements. -
China
Civil war in China -
James Chadwick
James Chadwick was the first man to discover the neutron, which is the neutrally charged particle of the nucleus. Electrons whizz around the nucleus on orbits. -
New Deal
Roosevelt begins "New Deal" -
Erwin Rudolf
Erwin Rudolf was a physicist, theoretical biologist, and a father of quantum mechanics. He received a Nobel Peace Prize in Physics in 1933 for his contribution of the Schrodinger equation. -
Paul Adrien Maurice Dirac
Dirac was an English physicist who made contributions to the developments of both quantum mechanics and electrodynamics. He formulated the Dirac equation, which describes the behavior of fermions, and predicted the existence of antimatter. -
Hitler
Adolf Hitler becomes
Fueher of Germany -
World War II
World War Two begins:
Germany invades Poland -
Aristotle
Aristotle, the tutor of Alexander The Great, believed in only the four elements air, earth, wind, and fire. He also believed that regardless of the number of times you cut any form of matter in half, you would always have a smaller piece of that matter.