2. 27-4 Photon Interactions; Compton Effect and Pair Production *A.H. Compton scattered (reflected) light from surfaces and found the scattered light had slightly lower frequency than the original light. *This is called the Compton effect. *This supported photon theory because of the photoelectric effect. See formulas p 833 *See Example 27-7 and photon interactions p 834

3. 27-5 Wave Particle Duality * The principle of complementarity says to understand any given experiment, you must use either wave or particle theory, but the two must complement one another.

4. 27-6 Wave Nature of Matter Louis de Broglie took the wave debate to another level when he stated that all matter has wave behavior. l =h/mv See example 27-9 and 27-10

5. 27-7 Electron Microscopes Electron microscope Transmission electron microscope Scanning electron microscope Scanning tunneling electron microscope Atomic force microscope

6. 27-8 Early Models of the Atom Atomists- basic building block was invisible Dalton’s Atomic Theory- indivisible atom JJ Thomson- electron Goldstein- proton Chadwick -1932-Neutron Niels Bohr- Quantum Mechanical Model

7. 27-9 Atomic Spectra-Key to atomic structure Atomic absorption spectra Atomic emission spectra See page 842 Balmer Series w/l = about 365 nm Lyman series w/l = 91-122 nm

8. 27-10 The Bohr Model Quantum Quantum or energy level number Bohr Radius (see p 845) Ground state/ excited state The minimum energy to remove an electron from a gaseous atom is binding energy or ionization energy. See Examples 27 11-14 p849

9. 27-11 de Broglies Hypothesis Applied to atoms See diagrams p 851

10. HW TXT27B Page 85 36-38,46,48-50 due Tuesday BOP