1. Electrons
Stability and Change

2. Review of Light Energy Wavelength Frequency
Photon—one particle of electromagnetic radiation…different colors have different energies associated with them

3. Electromagnetic spectrum

4. Mathematical Relationship
Frequency and wavelength are related by Plank’s constant and the speed of light.

5. Practice

6. So what causes colors?
Light energy hits an atom and “excites” electrons.
Electrons release energy as light.
What color light is
a larger release of energy? Purple
or Red?

7. Quantized vs. Continuous?
Energy released by atoms is “quantized” or in very discrete packets.

8. This has lead to the Bohr Model of the Atom
Orbital: 3-D area where it is likely an electron is located
Principle energy levels:
Represent location of electrons in “shells”
Correspond with rows on the periodic table.

9. Sublevels
Within an energy level, the location in 3-D space that the electron is likely to occupy.
Sublevel
Orbitals
Electrons/Orbital
Total # Electrons in Sublevel s 1 2 p 3 6 d 5 10 f 7 14

10. Sublevels in 3-D

11. How does this relate to the periodic table?
Where are the s, p, d electrons?

13. How does this relate to stability?
Location and filling of sublevels indicates stability of an atom and its likeliness to change!

14. Practice
Write the electron configuration for: He, Be, O, Cl, Ca, Ag, Kr

15. Cheat Sheet—You may use for now to get used to it!
Remember the max
amount of electrons
each sublevel can
hold!

16. Short-cut
The shorthand notation is to note the element by the noble gas in the row (period) before and the electron configuration for the outer shell.
Ex. Ca- 1s22s2p63s2p64s2
Ca- [Ar]4s2

17. Spin No two electrons in a given sublevel can occupy the same spin
Each electron in an orbital can be represented by up and down arrows

19. Stability and Change What seems to make atoms less stable?
How does spin relate to valence electrons?

20. Lab--
Since each atom has atoms at specific energy levels, each atom will emit a specific color (wavelength) of light when atoms absorb energy.
Heating atoms causes emission of light. These can be measured by a spectroscope

21. Spectroscope

22. Fireworks
What elements cause the colors of the many magnificent fireworks we see on the 4th of July?

23. Applications
Since each element or mix of ions has its own emission spectrum, this can act as a sort of fingerprint for determining makeup of elements.
How do they use this application on CSI and other crime shows?

24. What is the sun made of?
I will find out where she has goneAnd kiss her lips and take her hands;And walk among the dappled grass,And pluck till time and times are doneThe silver apples of the moon,The golden apples of the sun. ~Ray Bradbury
How did spectroscopy help us to figure out the composition of the sun?

25. Goal—To observe and identify the emission spectra of various ions and elements as a fingerprint. Finally to use this information to determine the composition of an unknown.