TIme Line of the Atom

  • Joseph Proust

    Joseph Proust
    Joseph Proust observed that specific substances always contain the same elements in the same ratio by mass. (Law of Definite Proportions)
  • Antoine Lavoisier

    Antoine Lavoisier
    Antoine Lavoisier found that a chemical change occurred in a closed system- the mass after a chemical change equaled the mass before the change.
  • John Dalton

    John Dalton
    John Dalton preformed experiment with various chemicals that found that matter consists of atoms based on 4 experiments, one of which was made by Lavoisier and another by Proust.
  • J.J. Thomson

    J.J. Thomson
    J.J. Thomson discovered the electron, and that electrons have a negative. He believed that matter has a positive charge.
  • The Curies

    The Curies
    Pierre Curie and his wife Marie Curie said that radioactive materials make atoms break down which releases radiation in the form of energy and subatomic particles.
  • Max Planck

    Max Planck
    Max Planck found that when atoms vibrate enough, you can only measure the energy in discrete units.
  • Erwin Shrodinger

    Erwin Shrodinger
    Erwin Shroedinger created the Shroedinger Equation (a wave equation that describes the form of the probability waves that govern the motion of small particles and how these waves are altered by external influences)
  • Albert Einstien

    Albert Einstien
    Albert Einstein thought that light was made up of different particles that had wavelike behavior and demonstrate certain properties unique to particles. He also brought forth the theory of relativity.
  • Robert Millikan

    Robert Millikan
    Robert Millikan obtained the first accurate measurement of an electrons charge.
  • Niels Bohrs

    Niels Bohrs
    Danish Physicist Niels Bohrs comes up with a new theory about how electrons are placed withing an atom. he comes up with 2 rules about it:
    RULE 1: Electrons can orbit only at certain allowed distances from the nucleus.
    RULE 2: Atoms radiate energy when an electron jumps from a higher-energy orbit to a lower-energy orbit. Also, an atom absorbs energy when an electron gets boosted from a low-energy orbit to a high-energy orbit.
  • Lord Rutherford

    Lord Rutherford
    The third particle in an atom is predicted by Lord Rutherford using alpha rays. He used Radium as the source of the alpha rays and shinned them onto thing gold foil to see the alpha particles impact. he thought that the negatively charged electrons orbited a center like the solar system.
  • Wolfgang Pauli

    Wolfgang Pauli
    Austrian Physicist wolfgand Pauli predicted that an electron spins on an axis as it orbits the nucleus
  • Walter Bothe

    Walter Bothe
    first evidence of the third particle was found by Walter Bothe in 1930
  • James Chadwick

    James Chadwick
    James Chadwick repeated bothe’s work and found high energy particles with no charge and essentially the same mass as the proton.
  • Otto Hahn

    Otto Hahn
    Otto Hahn discovers nuclear fission, where he nucleus of an atom breaks up into two separate nuclei, while experimenting with uranium
  • Murray Gell-Mann and George Zweig

    Murray Gell-Mann and George Zweig
    Murray Gell-Mann and George Zweig thought of "quarks", bits of matter which when used kind of like building blocks, which can explain certain complex chemical substances.