1. Light and electrons

2. Bohr’s planetary model
1913
Energy level of an electron can be compared to the rungs of a ladder
Electron cannot exist between energy levels, just like you can’t stand between rungs on ladder
Quantum of energy required to move to the a further, or higher, orbit

3. When electrons get the right amount of energy, they get excited and ‘jump” up to a higher energy level.
When they get tired,
they return to a lower
energy level and
release the energy as
a photon.

5. Heisenberg’s uncertainty principle: light behaves as both a particle and a wave. We can either know how fast it is moving, or where it is but not both at the same time.

6. Parts of a wave
Crest
Wavelength
Amplitude
Trough

7. Frequency
The number of waves that pass a given point per second.
Units: cycles/sec or hertz (hz or sec-1)
Abbreviated by Greek letter nu = n
n = c / λ
c = ln

8. Wavelength Represented by greek letter lambda λ
Wavelength = speed of light/frequency
λ = c/ ν
Wavelength and frequency are inverse, as one goes up other goes down

9. Electro-Magnetic Spectrum
Frequency 

10. White light
White light is made up of all the colors of the visible spectrum.
Passing it through a prism separates it.

11. If the light is not white
By heating an element with electricity it gives off a certain color.
Passing this light through a prism does not give a rainbow.

12. Atomic Spectrum
Each element gives off its own characteristic colors, like a “fingerprint.”
This can be used to identify the atom.

13. Emission Spectra These are called line spectra or emission spectra.
These spectra are unique to each element.

14. THE ELECTRONS! Why do we need to know this?
What causes the light colors?
THE ELECTRONS!

15. What is a quantum?
Max Planck suggested that the energy that objects either emit or absorb is restricted to certain sizes, or quanta.
Analogous to steps as compared to a ramp.
Quanta of light are called photons.
Planck related energy to waves by the following equation: E = hn, where h equals 6.63 x Js

16. Explanation of atomic spectra
The electron’s starting energy level is called it’s ground state- the lowest energy level.
The electrons move to an excited state by absorbing energy (heat or electricity).
When the electron “falls” back to a lower energy level, the energy lost is emitted as light.

19. Changing the energy Let’s look at a hydrogen atom
Ground State Electron

20. Changing the energy
Heat, electricity or light can “excite” electrons to higher energy levels

21. Changing the energy
As the electron falls back to ground state, it loses energy in the form of light

22. Changing the energy May fall down in steps, or large leaps
Each with a different energy

23. Energy of the photos
As the electrons make their quantum leaps and release energy as photons of light, it is possible to calculate the energy.
We can see that as frequency increases, energy increases. Max Plank studied this relationship and determined that the proportionality constant is x 108 J * s
Energy = h * ν or
Energy = planks constant * frequency