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Atomic Theory

  • 460 BCE

    Democritus born

    Democritus born
    Abdera, Greece
  • 400 BCE

    Democritus contributions

    Democritus contributions
    What they contributed:
    Promulgated the atomic theory, which asserted that the universe is composed of two elements: the atoms and the void in which they exist and move
    Democritus did not originate the atomic theory; he learned it from its founder, Leucippus, the author of the Big Cosmology.
    What experiments:
    Separated a seashell into its smallest components
  • 370 BCE

    Democritus death

    Democritus death
  • Antoine Lavoisier born

    Antoine Lavoisier born
    Paris, France
  • John Dalton born

    John Dalton born
    Eaglesfield, England
  • Antoine Lavoisier contributions

    Antoine Lavoisier contributions
    What they contributed:
    Defined law of conservation of mass
    This helped shape atomic theory b/c matter is composed of atoms that aren’t created or destroyed during chemical reactions
    What experiments:
    Heat and combustion of substances, reacted oxygen with inflammable air
  • Antoine Lavoisier death

    Antoine Lavoisier death
    Paris, France
  • John Dalton contributions

    John Dalton contributions
    What they contributed:
    All matter is made up of indivisible and indestructible atoms w distinct properties
    What experiments:
    Combined oxygen with two volumes of nitric oxide over water
  • John Dalton death

    John Dalton death
    Manchester, UK
  • J.J. Thomson born

    J.J. Thomson born
    Cheetham Hill, UK
  • Max Planck born

    Max Planck born
    Kiel, Germany
  • Marie Curie born

    Marie Curie born
    Warsaw, Poland
  • Robert Millikan born

    Robert Millikan born
    Morrison, Illinois, U.S.
  • Ernest Rutherford born

    Ernest Rutherford born
    Nelson, New Zealand
  • Albert Einstein born

    Albert Einstein born
    Uhm, Germany
  • Niels Bohr born

    Niels Bohr born
    Copenhagen, Denmark
  • Erwin Schrödinger born

    Erwin Schrödinger born
    Vienna, Austria
  • James Chadwick born

    James Chadwick born
    Manchester, UK
  • Louis De Broglie born

    Louis De Broglie born
    Dieppe, France
  • J.J. Thomson

    J.J. Thomson
    What they contributed:
    All atoms contain negatively charged subatomic particles or electrons
    Plum pudding model
    What experiments:
    Cathode rays were negatively charged
  • Max Planck contribution

    Max Planck contribution
    What they contributed:
    Quantum theory
    What experiments:
    Studied the diffusion of hydrogen through heated platinum
  • Werner Heisenberg born

    Werner Heisenberg born
    Wurzburg, Germany
  • Marie Curie contribution

    Marie Curie contribution
    What they contributed:
    Discovered polonium and radium
    What experiments:
    Studied mineral pitchblende
  • Robert Millikan contribution

    Robert Millikan contribution
    What they contributed:
    Accurate determination of the charge carried by an electron
    What experiments:
    Falling-drop method
  • Albert Einstein contribution

    Albert Einstein contribution
    What they contributed:
    Helped revolutionize the sciences with statistics and probability
    What experiments:
    Mathematically proved the existence of atoms
  • Ernest Rutherford contribution

    Ernest Rutherford contribution
    What they contributed:
    Mass of the atom is concentrated in its nucleus
    What experiments:
    Gold foil experiment
  • Niels Bohr contribution

    Niels Bohr contribution
    What they contributed:
    Proposed a theory for hydrogen atom based on quantum theory
    What experiments:
    Bohr model
  • Louis De Broglie contribution

    Louis De Broglie contribution
    What they contributed:
    Particles, such as electrons, could be described not only as particles but also as waves
    What experiments:
    Streams of electrons were reflected against crystals
  • Werner Heisenberg contribution

    Werner Heisenberg contribution
    What they contributed:
    Discovered the uncertainty principle
    What experiments:
    Formulated quantum mechanics in terms of matrices
  • Erwin Schrödinger contribution

    Erwin Schrödinger contribution
    What they contributed:
    Wave equation that calculates the energy level of electrons in atoms
    What experiments:
    Bohr’s orbit theory
  • James Chadwick contribution

    James Chadwick contribution
    What they contributed:
    Proved the existence of neutrons
    What experiments:
    Measured mass and performed an experiment that others were tinkering with
  • Marie Curie death

    Marie Curie death
  • Ernest Rutherford death

    Ernest Rutherford death
    Cambridge, UK
  • J.J. Thomson death

    J.J. Thomson death
    Cambridge, UK
  • Max Planck death

    Max Planck death
    Göttingen, Germany
  • Robert Millikan death

    Robert Millikan death
    Pasadena, California, U.S.
  • Albert Einstein death

    Albert Einstein death
    Princeton, New Jersey, U.S.
  • Erwin Schrödinger death

    Erwin Schrödinger death
    Vienna, Austria
  • Niels Bohr death

    Niels Bohr death
    Copenhagen, Denmark
  • James Chadwick death

    James Chadwick death
    Cambridge, UK
  • Werner Heisenberg death

    Werner Heisenberg death
    Munich, Germany
  • Louis De Broglie death

    Louis De Broglie death
    Paris, France