Atomic Theory : A Timeline<br />Melissa, Joe, Jake and Ryan<br />
Democritus (400 BCE)<br />Greek philosopher<br />Theorist, not scientist<br />Atomic Theory: <br />All elements made of at...
Lavoisier (1777)<br />French chemist<br />Provided formula for the conservation of matter in chemical reactions<br />Disti...
John Dalton (1803)<br />English chemist and schoolteacher<br />Discovered atoms<br />Atomic Theory:<br />All elements comp...
William Crookes (1870)<br />Created “Crooks’ Tube”<br />Demonstrated that cathode rays travel in straight lines and produc...
Eugene Goldstein (1886)<br />German physicist<br />Found rays traveling in the opposite of that of the cathode rays in a c...
J. J. Thompson (1897)<br />Discovered electrons<br />Cathode ray tube experiments<br />Hypothesized that cathode rays are ...
Robert Millikan (1908)<br />American experimental physicist<br />Determined quantity of charge on an electron<br />Used Th...
Ernest Rutherford (1911)<br />English physicist and chemist<br />Gold foil experiments<br />Atomic Theory:<br />Atom is mo...
Neil Bohr<br />Danish physicist<br />Stated electrons moved around the nucleus in successive, large orbits<br />Also prese...
James Chadwick (1932)<br />English physicist<br />Discovered neutrons<br />
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Atomic theory

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Atomic theory

  1. 1. Atomic Theory : A Timeline<br />Melissa, Joe, Jake and Ryan<br />
  2. 2. Democritus (400 BCE)<br />Greek philosopher<br />Theorist, not scientist<br />Atomic Theory: <br />All elements made of atoms<br />Atoms are indivisible, indestructible<br />
  3. 3. Lavoisier (1777)<br />French chemist<br />Provided formula for the conservation of matter in chemical reactions<br />Distinguished between elements and compounds<br />
  4. 4. John Dalton (1803)<br />English chemist and schoolteacher<br />Discovered atoms<br />Atomic Theory:<br />All elements composed of tiny, indivisible particles called atoms<br />Atoms of the same element are different from those of any other element<br />Atoms of diff. elements can mix physically or can chemically combine in simple whole-number ratios to form compounds<br />Chemical reactions occur when atoms are combined, separated, or rearranged<br />Atoms of one element are never changed into atoms of another element as a result of a chemical reaction<br />
  5. 5. William Crookes (1870)<br />Created “Crooks’ Tube”<br />Demonstrated that cathode rays travel in straight lines and produce phosphorescence and heat when they strike certain materials<br />
  6. 6. Eugene Goldstein (1886)<br />German physicist<br />Found rays traveling in the opposite of that of the cathode rays in a cathode ray tube<br />Called these “canal rays” (later renamed protons)<br />
  7. 7. J. J. Thompson (1897)<br />Discovered electrons<br />Cathode ray tube experiments<br />Hypothesized that cathode rays are tiny, negatively charged particles moving at high speeds (electrons)<br />Measured the charge to mass ratio of the electron<br />Atomic Theory:<br />Plum pudding model – negatively charged particles contained in a positively charged matrix<br />
  8. 8. Robert Millikan (1908)<br />American experimental physicist<br />Determined quantity of charge on an electron<br />Used Thompson’s charge to mass ratio to calculate the mass of the electron<br />Performed “oil-drop” experiments<br />
  9. 9. Ernest Rutherford (1911)<br />English physicist and chemist<br />Gold foil experiments<br />Atomic Theory:<br />Atom is mostly empty space<br />Small, positively charged nucleus<br />Electrons move around outside of the nucleus<br />Created nuclear model<br />
  10. 10. Neil Bohr<br />Danish physicist<br />Stated electrons moved around the nucleus in successive, large orbits<br />Also presented Bohr Atomic Model<br />Atoms absorb or admit radiation only when electrons abruptly jump between allowed, or stationary, states<br />
  11. 11. James Chadwick (1932)<br />English physicist<br />Discovered neutrons<br />

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