1. Electrons

2. Light
Properties of
Waves
Particles

3. Waves

4. Electromagnetic radiation
Energy
Travels like waves
All kinds speed of 3.00 x 108 m/s in a vacuum
Move repetitively
Measured properties
Wavelength
Frequency

5. Electromagnetic Spectrum

6. Wavelength Distance between two corresponding points on adjacent waves
Units = distance
Symbol = λ

7. Frequency
Number of waves that pass a point in a specific time normally 1 sec
Units = waves / second or Hz
Symbol = ν

8. Wavelength vs Frequency
The 2 properties are inversely related – as one goes up the other goes down
c = λν
c= speed of light (m/s)
λ = wavelength (m)
ν = frequency (1/s or Hz)
If you know one variable you can find the other
What is the frequency of a wave whose wavelength is 0.01m?

9. Particle Theory

10. Photoelectric Effect Emission of electrons when light strikes metal
Only happens when frequency of light is above a minimum amount for each metal
Intensity does not matter

11. Planck Objects release electromagnetic radiation in packets
1 packet = Quantum = smallest amount of energy gained or lost by an atom
The energy is related to the frequency of the wave
E = hν
E = energy in J
H = Plank’s constant (6.626 x J∙s)
ν= frequency

12. Planck Problem
E = hν
h = x J∙s (Plank’s constant)
Determine energy in joules of a photon w/ frequency of 1.29x1017Hz.

13. Einstein ER has wave and particle properties
Each particle has a quantum of energy
Photon – particle of ER with no mass and a quantum of energy
Matter absorbs energy ONLY in whole numbers of photons
To eject an electron from metal, the photons must have a minimum energy or a minimum frequency
Ephoton = hν

14. Line-Emission Spectrum
Ground state- lowest energy state of atom
Excited state- higher in potential energy than ground state
When electricity is run through a gas
Atoms get excited
Drop back to ground state
Light energy is released
If we look at that light through a prism it breaks down into the component colors of light called line-emission spectrum
Every element has own unique spectrum

15. H’s line-emission spectrum showed differences between energy states bare fixed
Electrons can only exist in certain energy states
Which leads to Bohr Model of atom

16. Bohr Model Electrons exist in certain energy levels around the nucleus
Closer to nucleus is lower energy
Further out higher energy
Cannot exist between energy levels

17. De Broglie Electrons act like both waves and particles
Act as confined waves, can only exist at certain frequencies
Can be interfered with