1. Charles Hakes Fort Lewis College1

2. Charles Hakes Fort Lewis College2 Chapter 2 Spectroscopy / Review

3. Charles Hakes Fort Lewis College3 Outline Test Wednesday Spectroscopy Check posted grades!

4. Charles Hakes Fort Lewis College4 Misc If you received a C- or below (or any grade you have questions about) for your mid-term grade, please come by my office to discuss your situation.

5. Charles Hakes Fort Lewis College5 Test Topics Chapter 0 - review Chapter 1 - review, and add 1.3 Kepler 1.4 Newton Chapter 2 - review, and add 2.4 Blackbody radiation 2.5 Spectroscopy Chapter 4 - The Solar System 4.1 inventory (review general properties) 4.2 debris (asteroids, meteoroids, comets) 4.3 solar system formation (nebular theory)

6. Charles Hakes Fort Lewis College6 Test Topics Chapter 5 - Earth and Moon Entire chapter (particularly atmospheres) Chapter 6 - Terrestrial Planets 6.3 and 6.8 atmospheres (supplement to 5.3) Other sections - just a quick read, on your own. Chapter 7 - just a quick read, on your own.

7. Charles Hakes Fort Lewis College7 Spectroscopy

8. Charles Hakes Fort Lewis College8 ROY G BIV

9. Charles Hakes Fort Lewis College9 ROY G BIV red orange yellow green blue indigo violet

10. Charles Hakes Fort Lewis College10 Figure 2.11 Spectroscope

11. Charles Hakes Fort Lewis College11 Figure 2.12 Emission Spectrum

12. Charles Hakes Fort Lewis College12 Figure 2.15 Absorption Spectrum

13. Charles Hakes Fort Lewis College13 Figure 2.16 Kirchhoff ’ s Laws

14. Charles Hakes Fort Lewis College14 Figure 2.13 Elemental Emission

15. Charles Hakes Fort Lewis College15 Figure 2.14 Solar Spectrum

16. Charles Hakes Fort Lewis College16 But where do those lines come from?

17. Charles Hakes Fort Lewis College17 Background At the end of the 19th century, many scientists believed that they had “discovered it all” and that only details remained to be filled in. (Like why are those spectral lines there.) Electromagnetic energy appears to come in “packets”, called photons. Particle nature of photons helps explain interactions with matter. Photon energy is directly proportional to frequency.

18. Charles Hakes Fort Lewis College18 Quantum Mechanics (How to build an atom)

19. Charles Hakes Fort Lewis College19 How to Build an Atom Components Proton - heavy, positive charge Neutron - heavy, no charge Electron - light, negative charge Number of protons defines element type (atomic number) Sum of protons and neutrons defines atomic weight

20. Charles Hakes Fort Lewis College20 How to Build an Atom Almost all atom mass is in the nucleus (protons and neutrons) Protons are held together by nuclear force. (Very strong, but very short range.) Protons (positive charge) make an “electromagnetic potential well.” (Attracts negative charges.) Electrons (negative charge) are attracted to the well and “fill it up” until you end up with a neutral atom.

21. Charles Hakes Fort Lewis College21 Figure 2.18 Modern Atom - note electron “ cloud ”

22. Charles Hakes Fort Lewis College22 Some Rules for Atoms No two electrons can be in the same state of the same atom at the same time. Only certain energy levels are allowed. Only photons with the same energy as the difference between allowed atomic states can be absorbed or emitted from an atom.

23. Charles Hakes Fort Lewis College23 Hydrogen Spectrum Transitions from excited state to ground state will emit ultraviolet light. Transitions from higher excited state to first excited state emit visible photons.

24. Charles Hakes Fort Lewis College24 Figure 2.19 Atomic Excitation

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29. Charles Hakes Fort Lewis College29 Figure 2.20 Helium and Carbon Allowed energy levels are much more complex when multiple electrons are involved. Allowed energy levels are much more complex when multiple nuclei are involved (molecules).

30. Charles Hakes Fort Lewis College30 Figure 2.21 Hydrogen Spectra - molecular and atomic Atomic spectrum shows the Balmer lines (the “H” lines) - H , H , H  etc 

31. Charles Hakes Fort Lewis College31 Review Questions?

32. Charles Hakes Fort Lewis College32 Three Minute Paper Write 1-3 sentences. What was the most important thing you learned today? What questions do you still have about today’s topics?