lecnotes02 - MIT OpenCourseWare http:/ocw.mit.edu 5.111...

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MIT OpenCourseWare http://ocw.mit.edu 5.111 Principles of Chemical Science Fall 2008 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms .
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5.111 Lecture Summary #2 Readings for today: A.2-A.3 (pgs F10-F13), B.1-B.2 (pgs F15-F18), and Section 1.1. Read for Lecture #3: Section 1.2 (1.1 in 3 rd ed ) – The Characteristics of Electromagnetic Radiation, Section 1.4 (1.2 in 3 rd ed )- Radiation, Quanta, and Photons (focus on pgs 10-12 in the 4 th ed or pgs 5-7 in the 3 rd ed ). Topics: I. Discovery of the electron and the nucleus II. (Failure of) the classical description of the atom Heading into the 20th century there was a feeling by many in the chemistry and physics communities that our scientific knowledge was nearly complete. It was universally accepted that atoms were the most basic constituent of matter and that the behavior of all matter could be explained through Newtonian mechanics. BUT …several discoveries and observations contradicted these theories: I. A) DISCOVERY OF THE ELECTRON J.J. Thomson (English physicist, 1856-1940) in 1897 discovers the electron and determines the charge to mass ratio. In 1906 he wins the Nobel Prize. The Experiment: deflection plate (+) ! V >> 0 cathode(-) anode(+) ! x deflection H 2 (g) cathode rays ! V = 0 deflection plate (-) high voltage difference cathode rays = _____________________-charged particles = electrons If Δ V (the voltage difference between the two deflection plates) = 0 there is no deflection, but when Δ V is large there is Δ x deflection towards the positive plate. From classical electromagnetism, Thompson knew that Δ x (-) _______ e (-) = ___________________ of the negative particle m (-) = __________________ of the negative particle 1
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BUT when a very large Δ V is applied a slight deflection towards the negative plate is
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This note was uploaded on 11/27/2011 for the course CHEMICAL E 20.410j taught by Professor Rogerd.kamm during the Spring '03 term at MIT.

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lecnotes02 - MIT OpenCourseWare http:/ocw.mit.edu 5.111...

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