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Unit 1: Atomic Structure AP Chemistry

Unit 1: Atomic Structure AP Chemistry. Evolution of Atomic Theory. Democritus – 400 B.C. Greek Philosopher Imagined particles that were indivisible Constituents of matter Atom comes from “atomos” Opposed Aristotle. Aristotle – 350 B.C.

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Unit 1: Atomic Structure AP Chemistry

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  1. Unit 1: Atomic StructureAP Chemistry Evolution of Atomic Theory

  2. Democritus – 400 B.C. • Greek Philosopher • Imagined particles that were indivisible • Constituents of matter • Atom comes from “atomos” • Opposed Aristotle

  3. Aristotle – 350 B.C. • Widely accepted theory that all matter can be continually divided. • Set science back for thousands of years.

  4. Alchemy • A pseudoscience that superceded scientific discoveries. • Alchemists attempted to turn metals into gold and developing the “elixir” of life (able to cause immortality and create life).

  5. Pierre Gassendi - 1650 • Reintroduced Particulate theory • No experimental evidence • Supported by Sir Isaac Newton

  6. Robert Boyle - 1661 • Studied Gases • 1st to use the term element in its current context in his book The Skeptical Chemist

  7. George Stahl - 1717 • Suggested “phlogiston” flowed from burning material • A necessary ingredient of combustible material

  8. Joseph Priestly - 1774 • discovered oxygen supports combustion

  9. Antoine Lavoisier - 1778 • Developed Law of Conservation of Mass • Explained combustion

  10. Joseph Proust - 1799 • Developed “Proust’s Law” using copper oxide • Later renamed, the Law of Definite Proportions • Nearly discovered the Law of multiple proportions, but his data used percentages instead of weights.

  11. John Dalton - 1802 • First to develop an atomic theory. It has 4 postulates. • Each element is made up of atoms • Atoms of the same element are identical in mass and properties. Atoms of different elements differ in some way.

  12. John Dalton - 1802 • Compounds are made when atoms combine. If elements combine in more than one whole number ratio, the resulting compound has different properties • Chemical reactions involve the reorganization of atoms.

  13. Amedeo Avogadro - 1811 • Developed Avogadro’s Law. Equal volumes of gases have equal number of molecules at constant temperature and pressure. • Expanded Dalton’s concept of atomic masses

  14. J.J. Berzelius - 1813 • Established the 1st system of using letters to represent elements.

  15. William Prout - 1815 • Proposed that Hydrogen was the fundamental material that all other elements were made from. All atomic masses were multiples of the mass of hydrogen.

  16. Michael Faraday - 1833 • Found Faraday’s Constant. 1 mole of e- = 96500 coulombs.

  17. Alexandre Béguyer de Chancourtois - 1862 • 1st periodic arrangement of elements. • Divided surface of a cylindrical base into 16 segments because oxygen has a mass of 16.

  18. John Newland - 1863 • Developed the law of octaves • Properties of elements repeat every eighth element.

  19. Dimitri Mendeleev - 1869 • Classification based on chemical properties. • Considered the first periodic table. • Left gaps for missing elements and predicted their properties

  20. William Crookes - 1879 • Showed that cathode rays stream from the negative pole

  21. Eugene Goldstein - 1886 • Discovered the proton using a cathode ray tube.

  22. William Roentgen - 1895 • Discovered x-rays. • Rays were penetrating and of short wavelength

  23. Henri Becquerel - 1896 • Discovered radioactivity. • Used uranium salts

  24. Marie Curie - 1897 • Student of Becquerel • Showed that radioactivity is atomic property • Isolated radium and polonium

  25. J.J. Thomson - 1897 • Determined the mass/charge ratio of the electron. • 5.69 x 10-9 • Used the cathode ray tube • Proposed a model of the atom that was mockingly called the “plum pudding” model

  26. Robert Millikan - 1909 • Determined the charge of the electron using the famous oil-drop experiment • 1.60 x 10-19 • From this and Thomson’s value, the mass was calculated to be 9.11 x 10-28g

  27. Ernest Rutherford - 1911 • Performed the famous gold foil experiment • Determined 3 things • The atom is mostly empty space • The nucleus is positively charged • The nucleus is a small dense part of the atom

  28. Gold Foil Experiment

  29. Gold Foil Experiment

  30. Henry Moseley - 1913 • Calculated atomic number by determining the nuclear charge of an atom.

  31. Niels Bohr - 1913 • Observed spectral lines for hydrogen • Proposed an orbit theory of the electron around the atom.

  32. Bohr Model

  33. Hydrogen Spectrum

  34. Gilbert Lewis - 1916 • Suggested that noble gases have 8 valence electrons • Atoms will gain or lose electrons to achieve 8 outer electrons.

  35. Louis De broglie - 1924 • Suggested that matter could exhibit wave properties • Observed diffraction patterns in electrons

  36. Wolfgang Pauli - 1924 • Pauli Exclusion Principle – 2 electrons cannot have the same 4 quantum numbers

  37. Erwin Schrödinger - 1926 • Developed a wave equation. • Mathematical function that described the nature of the electron

  38. James Chadwick - 1932 • Discovered the neutron

  39. Other Contributions • C.D. Anderson – 1932 • Discovered the positron • Enrico Fermi – 1940 • Prepared more than 40 radioactive elements

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