History of the Atom

By AvA182
  • Antoine Lavoisier 1783

    Antoine Lavoisier 1783
    He invented the analytical balance and showed that chemical elements were neither created nor destroyed, Also he discovered that water is made of hydrogen and oxygen
  • John Dalton 1803

    John Dalton 1803
    Believed the atom was based on measureable properties of mass.
  • Henri Becquerel 1896

    Henri Becquerel 1896
    While he was studying the effect of x-rays on photographic film, he stumbled into some chemicals that would spontaneously decompose and give off pentrating rays.
  • J.J Thompson 1897

    J.J Thompson 1897
    Studied "canal rays" and discovered that they were associated with the proton H + . he also discovered the mass ratio
  • Marie & Pierre Curie 1898

    Marie & Pierre Curie 1898
    Marie introduced the theory of radioactivity. Marie and Pierre discovered the radioactive elements Polonium and Radium.
  • Max Planck 1900

    Max Planck 1900
    Explained hot glowing matter using quanta.
  • Robert Millikan 1909

    Robert Millikan 1909
    He discovered the charge and mass of an electron by doing an oil drop experiment charge=(e=1.602 x 10 -19 coulomb) and the mass=(m = 9.11 x 10 -28 gram).
  • Ernest Ruthorford 1911

    Ernest Ruthorford 1911
    He discovered that the nucleus was very dense,very small and had a positive charge. He also assumed that the electrons were located outside the nucleus, he later on was proved to be correct.
  • Henry Moseley 1914

    Henry Moseley 1914
    He wrote "The atomic number of an element is equal to the number of protons in the nucleus". This later on became the structure of the periodic table instead of atomic mass.
  • Niels Bohr 1922

    Niels Bohr 1922
    Proposed a theory of the atomc structure, by using the periodic table. Introduced the theory that electrons orbit around the nucleus of an atom.
  • Erwin Schrodinger 1926

    Erwin Schrodinger 1926
    Believed that the atom was only made of waves, but not particles.
  • Werner Heisenberg 1927

    Werner Heisenberg 1927
    Proposed Principle of Indeterminancy - you can not know both the position and velocity of a particle.
  • James Chadwick 1932

    James Chadwick 1932
    Discovered the neutron, which he realized had a mass that was close to a proton
  • Democritus 400 B.C

    Democritus 400 B.C
    Believed atoms could be any size and that they were induvidually created and couldn't be seperated.
  • Aristotle 400 B.C

    Aristotle 400 B.C
    Aristotle believed that the atom was made from the portions of the four elements; water, fire, wind, and earth. He didn't believe that there wasn't a "smallest' part of matter.