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J. J. Thomson Discoverer of the Electron (1897)

J. J. Thomson Discoverer of the Electron (1897).

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J. J. Thomson Discoverer of the Electron (1897)

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  1. J. J. Thomson Discoverer of the Electron (1897)

  2. In J.J. Thomson’s experiments he was able to bend the cathode ray (which travels in a straight line) by applying either an electric field or a magnetic field. By finding the displacement of the ray he was able to calculate electric charge mass ratio the electron. And later that they were associated with the proton H+

  3. Using the Cathode Ray Tube, he presented 3 hypotheses: • Cathode rays are charged particles • These charged particles are part of the atom. • These particles are the only constituents of the atom

  4. Thomson’s Model of the Atom (1904) He described his atom as tiny negatively charged electrons that are embedded in a cloud of positive charge. He imagined the electrons are bits of plum in plum pudding. Today it is also explained to resemble a blueberry muffin or raisin pudding.

  5. Prior Knowledge Remember it was J.J. Thomson who identified that the atom was composed of positive and negative charges and had proposed that the atom was a solid mass of these particles.

  6. Significant Contributions to Atomic Theory 1900 -> 1930 • 1909 – 11 E. Rutherford, H. Geiger • 1913 R. A. Millikan • 1913 H. Moseley • 1919 N. Bohr • 1931 J. Chadwick

  7. 1909 – 1911 Ernest Rutherford and Hans Geiger

  8. The Gold Foil Experiment

  9. “It was quite the most incredible event that has ever happened in my life. It was almost as incredible as if you fired a 15 inch shell at a piece of tissue paper and it came back and hit you.” Ernest Rutherford

  10. Robert Milliken (1868 – 1953)

  11. Milliken's Chamber

  12. Henry Moseley(1887 – 1915)

  13. Mosley’s X-ray Experiment

  14. Moseley's Graph of Atomic Number

  15. Neils Bohr (1885-1962)

  16. No ..no . You are not thinking ; you are only being logical !! - Bohr 

  17. Neils Bohr Atomic ModelNiels Bohrapplies quantum theory to Rutherford's atomic structure.

  18. James Chadwick(1891 - 1974)

  19. “Old” Explanation of Atomic Mass

  20. “New” Explanation of Atomic Mass

  21. The End of Group 3’s Presentation Next 1930’s -> ……… “Closing the book on Atomic Theory?”

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