1. THE BOHR MODEL OF THE ATOM October 23, 2009

2. The Bohr Model of Hydrogen Atom Light absorbed or emitted is from electrons moving between energy levels Only certain energies are observed Therefore, only certain energy levels exist  Energy levels are Quantized

3. Energy Adsorption/Emission

4. Absorption and Emission Spectra

5. Hydrogen Energy Levels Constant = Rhc = 2.18 x 10 -18 J R = Rydberg constant = 1.0974 x 10 7 m -1 h = Planck’s constant = 6.626 x 10 -34 Js c= velocity of light in vacuum = 3.0 x 10 8 m/s

6. Each line corresponds to a transition: Example: n=3  n = 2

7. Balmer series Explanation of line spectra

8. The emission line with the shortest wavelength is: 1. 1 2. 2 3. 3 4. 4 5. 5

9. The emission line with the longest wavelength is: 1. 1 2. 2 3. 3 4. 4 5. 5

10. The emission line with the highest energy is: 1. 1 2. 2 3. 3 4. 4 5. 5

11. The absorption line with the shortest wavelength is: 1. 1 2. 2 3. 3 4. 4 5. 5

12. The absorption line with the lowest energy is: 1. 1 2. 2 3. 3 4. 4 5. 5

13. A Revolutionary Idea: Matter Waves All matter acts as particles and as waves. Macroscopic objects have tiny waves- not observed.  Wave nature only becomes apparent when object is VERY light For electrons in atoms, wave properties are important. deBroglie Equation:

14. Matter waves- Examples Macroscopic object: 200 g rock travelling at 20 m/s has a wavelength: Electron inside an atom, moving at 40% of the speed of light (0.4 x 3x10 8 m/s):

15. Can see matter waves in experiments