History Of The Atom

By 17schaeferst
  • 400

    Democritus 400bc

    Democritus 400bc
    All matter was made up of invisible and indestructable particles.

  • Antoine Lavoisier

    Antoine Lavoisier
    Discovered that water was made of hydrogen and oxygen.

  • John Dalton 1803

    John Dalton 1803
    Matter is made up of atoms that are invisible and indestructable. All atoms of an element are identical. Atoms of different elements have different weights and different chemical properties. Atoms of different elements combine in simple whole numbers to form compounds. Atoms cannot be created or destroyed. When a compoind decomposes, the atoms are recovered unchanges.

  • Dmitri Mendeleev 1869

    Dmitri Mendeleev 1869
    Arranged elements into 7 groups with similar properties. discovered the periodic law, which states that properties of elements were periodic functions of their atomic weights.

  • Eugen Goldstein 1886

    Eugen Goldstein 1886
    Used a CRT to study canal rays, which had electical and magnetic properties opposite of an electron.

  • JJ Thomson 1897

    JJ Thomson 1897
    Discovered the electron. designed a signature of electic discharge in a high-vaccum cathode-ray tube.

  • Max Planck 1900

    Max Planck 1900
    Showed that when you heat an object until it glows, you can measure the energy in discrete units that he called quanta.

  • Robert Millikan 1910

    Robert Millikan 1910
    Determined the electric charge carried by an electron.

  • Ernest Rutherford 1911

    Ernest Rutherford 1911
    Nucleus is very dense, very small, and positively charged. also discovered that electrons are located outside of the nucleus, orbiting around the nucleus.

  • Niels Bohr 1912

    Niels Bohr 1912
    Wrote papers on the absorption of alpha rays. showed us what a picture of the atomic structure looks like.

  • Henry Moseley 1914

    Henry Moseley 1914
    Determined charges on the nuclei of most atoms using x-ray tubes. his discovery that "the atomic number of an element is equal to the number of protons in the nucleus," was used to reorganize the periodic table by atomic number instead of atomic mass.

  • Werner Heisenberg 1927

    Werner Heisenberg 1927
    Proposed principal of indeterminancy which states that you can't know both the position and velocity of a particle.

  • Erwin Shrodinger 1930

    Erwin Shrodinger 1930
    viewed electrons as coontinuous clouds and introduced wave mechanics as a mathematical model of the atom.

  • James Chadwick 1932

    James Chadwick 1932
    Proved the existence of neutrons by heating nuclei and a elementary particle that had electical charges.