Timeline of the Atom

By nolasmith
  • 430 BCE

    Democritus

    Democritus (460 BCE - 370 BCE)
    Started the idea of an atom and the belief that they were solid uncuttable particles
  • 425 BCE

    Battle of Pylos (World Event)

    The Athenians beat Sparta in the Battle of Pylos

  • John Dalton

    John Dalton
    John Dalton (1766 - 1844)
    Created the theory that each element has its own individual atoms, that differ between the elements
    (picture shows his "marble" model)

  • Louisiana - Missouri Territory (World Event)

    Louisiana-Missouri Territory is established in America after the Louisiana Purchase

  • Michael Faraday

    Michael Faraday (1791 - 1867)
    Discovered that atoms have an electrical charge using reactions in electrolysis

  • Eugen Goldstein

    Eugen Goldstein (1850 - 1930)
    Discovered that atoms have positively charged particles (protons)

  • Treaty of Paris (World Event)

    The Spanish-American war ends after the signing of the Treaty of Paris

  • JJ Thomson

    JJ Thomson
    JJ Thomson (1856 - 1940)
    Discovered that atoms have negatively charged particles (electrons)
    (picture shows the "plum pudding model")

  • Robert Milikan

    Robert Milikan (1868 - 1953)
    Successfully discovered the magnitude of the electron’s charge using charged oil drops

  • Ernest Rutherford

    Ernest Rutherford
    Ernest Rutherford (1871 - 1937)
    Discovered that the atom is mostly empty space, but has a positively charged mass in the center nucleus
    (picture to left is the "jimmy neutron" model, picture to right is the "nuclear" model)

  • Neils Bohr

    Neils Bohr
    Neils Bohr (1885 - 1962)
    Began the theory that electrons in an atom could only occupy fixed orbits revolving around the nucleus
    (picture shows the "solar system" model)

  • 19th Amendment (World Event)

    The 19th Amendment was passed giving women the right to vote in America

  • Edwin Schroedinger

    Edwin Schroedinger
    Edwin Schroedinger (1887 - 1961)
    Discovered an equation that calculated the wave behavior in electrons

  • Werner Heisenberg

    Werner Heisenberg (1901 - 1976)
    Discovered the force that holds atoms together using quantum mechanics

  • The Great Depression (World Event)

    The Great Depression started in America, led to mass economic decline

  • James Chadwick

    James Chadwick
    James Chadwick (1891 - 1974)
    Discovered that atoms also have particles with no electric charge (neutrons)

  • WWII (World Event)

    World War II began