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Timeline of the Atom From “ Atomos to Clouds”

Timeline of the Atom From “ Atomos to Clouds”. Democritus. 400 B.C.E. Proposed that matter was composed of tiny indivisible particles Based on thought not experimentation Greek: “ atomos ”. Aristotle. 350 B.C.E. 4 element theory Matter infinitely divisible

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Timeline of the Atom From “ Atomos to Clouds”

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  1. Timeline of the AtomFrom “Atomos toClouds”

  2. Democritus • 400 B.C.E. • Proposed that matter was composed of tiny indivisible particles • Based on thought not experimentation • Greek: “atomos”

  3. Aristotle • 350 B.C.E. • 4 element theory • Matter infinitely divisible • All matter made of different amounts of the 4 elements

  4. Alchemists • 500BCE to 1720 • Mixture of science and mysticism. • Lab procedures were developed, but alchemists did not perform controlled experiments like true scientists.

  5. Sir Francis Bacon • 1620’s • Hypotheses based on evidence, experiments • Scientific Method • The birth of science as we know it

  6. Benjamin Franklin • 1700’s • Experiments with electricity • Arbitrarily decides positive and negative charge • Attraction between opposing charge

  7. Antoine Lavoisier • 1777 • Isolated “Elements” that could not be broken down further • Father of Modern Chemistry • Theorized how elements become compounds • Famous for parlor tricks

  8. Charles Augustin de Coulomb • 1780’s • Some fluids repelled, some attracted • Idea of charge

  9. John Dalton • 1803 • Water same Everywhere • Compounds happen in definite whole number ratios • Atomic Theory • Disproved Alchemy

  10. Daltons Atomic Theory Postulate 1 Postulate 2 All matter is made of atoms A chemical reaction is a rearrangement of atoms All atoms of an element are identical in mass and property Compounds are formed of two or more types of elements Atoms are indivisible and indestructible Postulate 3 Postulate 4 Postulate 5

  11. Sir William Crookes • 1870’s • Cathode Ray Tube (CRT) • Later used to find electrons

  12. Henri Becquerel • 1896 • Accidentally discovered Radiation • Set up experiment on photo plates but was exposed before light hit them

  13. Marie and Pierre Curie • 1898 • Defined radiation as atoms breaking down and emitting parts spontaneously • Discovered many radioactive elements

  14. JJ Thomson • 1898 • Discovered Crooke’s beam was negatively charged by deflecting with a magnet • Discovered the beam was particles by including paddlewheel

  15. JJ Thomson • Plum Pudding Model • Raisin Bread Analogy

  16. Max Planck • 1900 • Energy is emitted in small discrete amounts he called quanta • Planck’s constant

  17. Albert Einstein • 1905 • Special Theory of Relativity • Particle Nature of Light

  18. Robert Milikan • 1910 • Found Charge of e- • Oil Drop Experiment

  19. Ernest Rutherford • 1909 - 1911 • Gold Foil Experiment • Plum Pudding?????

  20. Gold Foil Experiment • Experiment Animation

  21. Rutherford Model • Nuclear Model • dense, positive nucleus surrounded by negative electrons

  22. Neils Bohr • 1913 • Bright-Line Spectrum • tried to explain presence of specific colors in H spectrum • Energy Levels • electrons can only exist in specific energy states

  23. Neils Bohr • Bright-Line Spectrum • Planetary or Solar System Model • electrons move in circular orbits within specific energy levels

  24. Louise DeBroglie • 1924 • Research in Quantum Theory • Particle/Wave Duality • “Wavicle or Partave”

  25. Erwin Schrodinger • 1926 • Wave nature of e- • The beginning of Quantum Mechanical Model of aton • New Problems

  26. Erwin Schrodinger • Quantum mechanics • electrons can only exist in specified energy states • Electron cloud model • orbital: region around the nucleus where e- are likely to be found

  27. Erwin Schrodinger Electron Cloud Model (orbital) • dots represent probability of finding an e-not actual electrons

  28. Schrodinger’s Cat

  29. James Chadwick • 1931 • Finds mass of Proton • Irene Joliot Curie • 1931 • Finds Neutron

  30. Glen Seaborg • 1951 • Transuranic Elements

  31. Murray Gell-Mann & George Zweig • 1964 • Particles in Protons & Neutrons • 6 types

  32. He Murray Gell-Mann & George Zweig less mass more mass • 3 quarks = 1 proton (2+, 1-) or 1 neutron (1+, 2-)

  33. What Does the Future Hold?

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