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Learn about the properties of electromagnetic radiation waves, the energy of photons, electron transitions in the Bohr model, and the hydrogen emission lines. Provide feedback and suggestions for improvement.
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Electromagnetic Radiation February 26, 2007 Chem 102B
Hydrogen Emission Spectrum • High-energy sparks inside a tube containing hydrogen gas (H2) cause the H-H bond to break, leaving atomic hydrogen. • The atomic hydrogen is excited, and when it relaxes it releases energy in the form of light.
Properties of waveswavelength = λfrequency = νspeed = cc = speed of light2.9979 x 108 m/s
Energies of a photon • Electromagnetic radiation travels in waves that are packaged into photons (quantum). • Given frequency (ν) or wavelength (λ) you can calculate the energy of a single photon. • E = hν = hc/λ • If the photon has energy does it have mass? • If an electron is in motion, does it have a λ?
Energy of the hydrogen emission lines • Each emission line is associated with a specific energy. • E = hc/λ
Bohr Model • Electrons orbit the nucleus • Only certain orbits are allowed. (n=1,2,3,4 . . .∞) • Energy of the orbit is • En=-Z2RH/n2 • Electrons move from one orbit to another by absorbing or emitting light.
Anonymous Evaluation Time • What have you liked so far about the course? • What suggestions do you have for improvement of the course? • Are you able to read the material presented on the chalk board and/or do you want more powerpoint talks? • What can Dr. Richmond do to help facilitate your learning? • What do you need to do to improve your course performance? • Other comments (TAs, quizzes, tests, homework, Lon-Capa, etc.)