1. Ground State vs. Excited State Ground State – all electrons are in the lowest possible energy levels (normal) ex. 2 – 8 – 18 – 32 Excited State – if given additional energy, electrons will “jump up” to higher energy levels, temporarily. Excited State ex. 2 – 5 – 2 Ground State ex. 2 – 7

2. Spectra (bright line) (dark line)

3. Bright Line = Emission Spectra How does this happen? “Excited electrons” at higher energy levels will eventually release the extra energy and “fall back down” to ground state conditions. During the “fall back”, energy is released as Visible Light Energy. Wavelengths = Energy = Color Bands

4. Bright Line Spectra

5. Energy levels are NOT evenly separated.

6. Bright Line – Emission Spectra

7. How are spectra formed?

8. Niels Bohr 1913 Danish chemist Bohr model of atom: http://www.chemeng.uiuc.edu/~alkgrp/mo/gk12/q uantum/ http://www.chemeng.uiuc.edu/~alkgrp/mo/gk12/q uantum/

9. Bright Line Spectra

10. Each element has a specific electron configuration and a corresponding emission spectrum. Emission (bright line) spectrum can be used to identify (“fingerprint”) each element. http://www.colorado.edu/UCB/AcademicAffairs/ArtsSci ences/physics/PhysicsInitiative/Physics2000/applets/a 2.html http://www.colorado.edu/UCB/AcademicAffairs/ArtsSci ences/physics/PhysicsInitiative/Physics2000/applets/a 2.html

11. So Dude, check out the colors! Do the spectra lab.

12. Bright Line – Emission Spectra

13. Spectra (bright line) (dark line)

14. Flame Tests - burn metal salts in a flame and observe/record the color - compare colors to known standards for metals - spectrascope not required

15. Sodium (Na) – Yellow flame with Na salts like NaCl, NaBr Potassium (K) – Violet flame with KCl, KBr, etc.