Quantum mechanics is a new way of understanding the atomic world based on quanta or packets of energy. Light can behave as both a particle and a wave, with photons as quanta of light energy. The photoelectric effect and emission line spectra provided evidence that light behaves as quanta that can be absorbed or emitted in specific amounts of energy. Bohr's model of the hydrogen atom explained transitions between discrete energy levels by quantization of angular momentum and energy.

1. Quantum Mechanics Parima Shah and Jasmine Wang (In less than 20 minutes)

2. Quantum Mechanics? Well, not anymore Ugh.

6. The anatomy of a Wavelength

8. Let’s see if this recipe actually works… Banana Bread Cheese Cake: Strawberry Wavelength & Frequency are related c= νλ c =3.00 x 10 8 m/s ν = frequency in /s λ = wavelength in m Frequency and wavelength formula

9. Time to cook: Solution: λ =c/ υ What is the wavelength of a yellow sodium emission of frequency 5.09 x 10 -7 /s? = 5.89 x 10 14 m

13. Lenard’s Photoelectric Experiments: Paradise. (not really)

15. Lenard’s Photoelectric Experiments: Paradise. (not getting realer) The kinetic energy in each “escaping” electron does not increase with intensity. In other words, intensity does not matter on the speed of the electrons. More and more sand was being dislodged, but no more violently than the weaker waves

16. Does this make sense in the world of physics? Does that make sense for waves? Lenard’s Photoelectric Experiments: Paradise. (nope) Does this make sense in the world of physics? Does this make sense in the world?

17. NO! Nada, Goose egg, a cookie, etc. etc.

19. The Photoelectric Effect The ejection of electrons from the surface of a metal from another material when light shines on it. Einstein adapted Planck’s quanta theory Photons- Quanta of light E= h ν where E is energy and h is Planck's constant of The amount of energy of each photon is miniscule. Light on sodium metal in vacuum Electrons ejected from the surface SODIUM METAL

21. Bohr’s Theory of the Hydrogen Atom Energy Level Postulate : electrons can have only specific energy values in an atom, called energy levels. Bohr’s rule for the quantization of a electron in the hydrogen atom :

22. Transitions between Energy Levels : An electron can change energy by transferring one energy level to another energy level. The emission of light from the atom occurs when the electron in a higher energy level moves to a lower energy level. The electron loses energy, which is emitted as a photon. Bohr’s Theory of the Hydrogen Atom

24. Solution to Example Problem