Unit 1: Atomic Structure AP Chemistry

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Unit 1 Atomic StructureAP Chemistry

• Evolution of Atomic Theory

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Democritus 400 B.C.

• Greek Philosopher
• Imagined particles that were indivisible
• Constituents of matter
• Atom comes from atomos
• Opposed Aristotle

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Aristotle 350 B.C.

• Widely accepted theory that all matter can be
  continually divided.
• Set science back for thousands of years.

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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• A pseudoscience that superceded scientific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).

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Pierre Gassendi - 1650

• Reintroduced Particulate theory
• No experimental evidence
• Supported by Sir Isaac Newton

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Robert Boyle - 1661

• Studied Gases
• 1st to use the term element in its current
  context in his book The Skeptical Chemist

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George Stahl - 1717

• Suggested phlogiston flowed from burning
  material
• A necessary ingredient of combustible material

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Joseph Priestly - 1774

• discovered oxygen supports combustion

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Antoine Lavoisier - 1778

• Developed Law of Conservation of Mass
• Explained combustion

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Joseph Proust - 1799

• Developed Prousts 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.

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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.

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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.

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Amedeo Avogadro - 1811

• Developed Avogadros Law. Equal volumes of gases
  have equal number of molecules at constant
  temperature and pressure.
• Expanded Daltons concept of atomic masses

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J.J. Berzelius - 1813

• Established the 1st system of using letters to
  represent elements.

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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.

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Michael Faraday - 1833

• Found Faradays Constant. 1 mole of e- 96500
  coulombs.

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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.

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John Newland - 1863

• Developed the law of octaves
• Properties of elements repeat every eighth
  element.

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Dimitri Mendeleev - 1869

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

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William Crookes - 1879

• Showed that cathode rays stream from the negative
  pole

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Eugene Goldstein - 1886

• Discovered the proton using a cathode ray tube.

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William Roentgen - 1895

• Discovered x-rays.
• Rays were penetrating and of short wavelength

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Henri Becquerel - 1896

• Discovered radioactivity.
• Used uranium salts

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Marie Curie - 1897

• Student of Becquerel
• Showed that radioactivity is atomic property
• Isolated radium and polonium

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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

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Robert Millikan - 1909

• Determined the charge of the electron using the
  famous oil-drop experiment
• 1.60 x 10-19
• From this and Thomsons value, the mass was
  calculated to be 9.11 x 10-28g

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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

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Gold Foil Experiment
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Gold Foil Experiment
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Henry Moseley - 1913

• Calculated atomic number by determining the
  nuclear charge of an atom.

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Niels Bohr - 1913

• Observed spectral lines for hydrogen
• Proposed an orbit theory of the electron around
  the atom.

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Bohr Model
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Hydrogen Spectrum
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Gilbert Lewis - 1916

• Suggested that noble gases have 8 valence
  electrons
• Atoms will gain or lose electrons to achieve 8
  outer electrons.

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Louis De broglie - 1924

• Suggested that matter could exhibit wave
  properties
• Observed diffraction patterns in electrons

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Wolfgang Pauli - 1924

• Pauli Exclusion Principle 2 electrons cannot
  have the same 4 quantum numbers

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Erwin Schrödinger - 1926

• Developed a wave equation.
• Mathematical function that described the nature
  of the electron

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James Chadwick - 1932

• Discovered the neutron

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Other Contributions

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