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Unformatted text preview: Chapter 15 Duality of Matter Quiz: Did you read Chapter 15 for today? ) es a) Yes b) No Earth Quiz: Suppose a Bohr atom has 1 electron and 4 states. How many different colors of emission lines will it have? a) 2 =4 b) 3 c) 4 d) 5 e) 6 n=1 n=2 n=3 n=4 Light is A. Energy that travels through space as a wave. B. A stream of particles that arries energy with it. carries energy with it. C. A unique entity that exhibits both wave and particle properties. In the Bohr model of the atom, electrons A. orbit only at specific distances from the nucleus. B. can have any sized orbit just like planets orbiting the sun. C. are embedded into a positively charged “pudding” like substance. Matter Models continued… s Two puzzles remain at this point: • The wave-particle duality of light. • The physical basis for the Bohr model. s In 1923 a struggling graduate student named Louis deBroglie proposed that moving matter also has a wave-particle duality defined from wavelength = h/(mass × speed) where h = Plank’s constant = 6 x 10-34 kg- m 2 /sec Examples Wavelength = 10-38 m (nonsense?) avelength = 10 4 ruck @ 60 mph Wavelength = 10-34 m (again nonsense?) Wavelength = 10-10 m which is the diameter of an atom. Now we are getting somewhere… Truck @ 60 mph Baseball @ 100 mph- Electron @ 2,000 m/sec But are electrons really waves? s S e e i f t h e y d i f f r a c t a n d i n t e r f e r e ! We need slits about the size of the electron wavelength (10-10 m) to witness diffraction. s How do you make a slit t h a t small? You don’t. You use the space between atoms in a crystal....
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This note was uploaded on 11/30/2011 for the course PHY S 100 taught by Professor Staff during the Winter '08 term at BYU.
- Winter '08