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Evolution of models of atomic structure – Breakdown of classical physics

Explore the timeline of the evolution of atomic structure models, from the ancient theories of Demokritus, Plato, and Aristoteles to the groundbreaking discoveries of Joseph John Thompson, Robert A. Millikan, Niels Bohr, and Louis de Broglie. Discover how these models shaped our understanding of atoms and their properties.

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Evolution of models of atomic structure – Breakdown of classical physics

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  1. Evolution of models of atomic structure – Breakdown of classical physics Atoms: atomo (Greek) indivisible first speculative atomistic theories by Demokritus Plato Aristoteles (460 – 370 BC) (429 – 348 BC) (384 – 322 BC) < pictures from www.wikipedia.org >

  2. ... more than 2000 years later ... Law of definite proportions (1794) by Joseph Louis Proust (1754 – 1826) First table of atomic weights (1803) by John Dalton (1766 – 1844) < pictures from www.wikipedia.org >

  3. ... more than 2000 years later ... 1833: “atomic properties” of electricity in electrolysis found by Michael Faraday (1791-1861) < picture from www.wikipedia.org >

  4. How indivisible are atoms? Joseph John Thompson (1865 – 1940) works with “cathode rays” 1897 he discovers that the charged particles in cathode rays have negative charge. He measures their charge-to mass ratio and identifies them as “electrons” postulated 1874 by G. Johnston Stoney as units of charge. - + 10 kV < picture from www.wikipedia.org >

  5. 1909 Robert A. Millikan (1868 – 1953) measures the magnitude of the elementary charge Nobel Prize 1923 < picture from www.wikipedia.org >

  6. Thompson’s Plum Pudding Model raisins pudding electrons are discrete particles embedded in a smeared out positive background charge < picture from www.wikipedia.org >

  7. Rutherford’s Experiment Scattering Intensity (arb. units) random walk (Thompson model) [°] Rutherford model from Gerthsen, Kneser, Vogel: “Physik”

  8. Emission Spectra Emission spectrum of Hydrogen Emission spectrum of Iron

  9. 1913: Bohr’s Model of the Atom Niels Hendrik David Bohr 1885 - 1962 Nobel Prize for Physics, 1922 < pictures from www.wikipedia.org >

  10. Matter Waves Louis Victor Pierre Raymond, 7e Duke of Broglie (1892 - 1987) Nobel Prize for Physics, 1922 < picture from www.wikipedia.org >

  11. Superimpose 2 waves with different momenta:

  12. Superimpose 10 waves with different momenta:

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