1. 1810
  2. 1900
  3. 1904
  4. 1905
  5. 1909
  6. 1911
  7. 1913
  8. 1924
  9. 1926

  1. John Dalton

    Billiard Ball Model

    Reignited the theory of the atom and the idea that the atom is indivisible and the smallest unit of matter.


  2. Max Planck

    Quantization of Energy

    Concluded that energy must be quantized and began the theory of quantum physics.

  3. J.J Thomson

    Plum Pudding Model

    Using a cathode ray tube, showed that there are negatively charged parts of the atom which would lead to the discovery of the electron.

  4. Albert Einstein

    Mass-Defect

    Concluded that energy and mass are equivalent and can be converted into one another.

  5. Robert Millikan

    Charge of Electron

    Determined the exact charge of electron through oil drop experiment, also found that this quantity was the same for all electrons.

  6. Ernest Rutherford

    Planetary Model

    Discovered alpha and beta radiation, also discovered that atoms are mostly empty space with his gold alpha particle scattering experiment. Came up with idea that the nucleus is also made up of particles, or positively charged protons.


  7. Niels Bohr

    Energy Level Model

    Using the hydrogen atom, found that only certain wavelengths of radiation were produced and therefore came up with energy level theory, where electrons exist at certain energy levels around the nucleus


  8. Louis de Broglie

    Wave Mechanical Model

    Theorized electron wave-particle duality by observing wave-like properties from electrons. helped to answer the question of accelerating particles not producing emr from the earlier models.


  9. Erwin Schrödinger

    Quantum Mechanical Model

    Formulated wave equation that could accurately calculate energy level of electrons. He also contributed to wave theory of matter.



    Sources: Physics Second Edition, J. Allum & Christopher Talbot; Pearson Physics Level 30