Che 131 Notes Ch. 2

Che 131 Notes Ch. 2 - Che 131 Notes Chapter 2: Atoms and...

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Che 131 Notes Chapter 2: Atoms and Elements Lecture 4: Atoms Reading 2.1-2.5 I. 2.1 Atomic Structure and Subatomic Particles A. Henri Becqueri 1896: a uranium ore emitted rays that exposed a photographic plate 1. suggested atoms of like elements spontaneously emit rays i. radioactivity C. radioactive elements emit 3 kinds of rays 1. alpha α, beta β a. deflected when passed between electrically charged plates b. charged particle i. α +2, β +1 c. has mass, is a particle d. shows that radioactive atoms can break apart to produce subatomic particles i. must be something smaller inside atoms 2. gamma γ a. not deflected when passed between electrically charged plates b. no detectable charge or mass i. behave like light rays D. cathode-ray tubes 1. provide evidence that atoms are composed of subatomic particles 2. cathode rays found to be streams of electrons E. Sir John Thomson 1. Suggested that cathode rays consist of electrons 2. 1897: calculated the ratio of mass to charge for electrons in cathode-ray beam a. 5.60 x 10 -9 grams per coulomb (g/C) F. Robert Millikin 1901: measured the charge of an electron (oil drop experiment) 1. 1.60 x 10 -19 C II. 2.2 The Nuclear Atom A. Ernest Rutherford 1910-1911: gold foil experiment 1. all of the positive charge and most of the mass of the atom are concentrated in a very
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Che 131 Notes Ch. 2 - Che 131 Notes Chapter 2: Atoms and...

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