History of the Atomic Theory

By alpha361
  • 370 BCE

    Democritus

    Greatest Contribution to Modern Science was the atomic theory he elucidated. According to his theory, the universe and all matter obey the following principles: Everything is composed of “Atoms” Root word: “A Tomos” meaning indivisible.
  • 322 BCE

    Aristotle

    Aristotle disagreed with Democritus’ Theory. He was not a scientist but a philosopher who believed that everything could be solved by simply thinking about the problem at hand.

  • JJ Thomson

    JJ Thomson, who discovered the electron in 1897, proposed the plum pudding model of the atom in 1904 before the discovery of the atomic nucleus in order to include the electron in the atomic model. In this model the atom was also sometimes described to have a “cloud” of positive charge.

  • Joseph Lucas

    Positive ground depends on proper circuit functioning, which is the transmission of negative ions by retention of the visible spectral manifestation known as "smoke". The function of the wiring harness is to conduct the smoke from one device to another

  • Plum Pudding Model

    The plum pudding model is one of several scientific models of the atom. First proposed by J. J. Thomson in 1904[1] soon after the discovery of the electron, but before the discovery of the atomic nucleus, the model represented an attempt to consolidate the known properties of atoms at the time: 1) electrons are negatively-charged particles and 2) atoms are neutrally-charged.

  • Marie and Pierre Curie

    For their joint research into radioactivity, Marie and Pierre Curie were awarded the 1903 Nobel Prize in Physics. As a team, the Curies would go on to even greater scientific discoveries. In 1898, they announced the discovery of two new elements, radium and polonium

  • Robert Millikan

    Robert Andrews Millikan (March 22, 1868 – December 19, 1953) was an American experimental physicist honored with the Nobel Prize for Physics in 1923 for the measurement of the elementary electronic charge and for his work on the photoelectric effect.

  • Albert Einstein

    Einstein treated matter and energy as exchangeable. Albert Einstein became famous for the theory of relativity, which laid the basis for the release of atomic energy. In 1905 Albert Einstein formulates Special Theory of Relativity.

  • Niels Bohr

    In 1913, Niels Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted.

  • James Chadwick

    His updated theory composed of sub-energy levels, Until 1932, the atom was believed to be composed of a positively charged nucleus surrounded by negatively charged electrons, In 1932, James Chadwick bombarded beryllium atoms with alpha particles. An unknown radiation that was produced.