1. Waves and light

2. Electronic Transitions
Light can be absorbed or transmitted by atoms

3. Subatomic Particles
All subatomic particles, and light act as both particles and waves
Referred to as ‘wave-particle duality’
Davisson and Germer first performed the ‘double slit experiment’ in 1932 which proved this

4. Double Slit Experiment

5. Light is Electromagnetic Radiation
As light propagates (travels) it emits both an electric field and a magnetic field
We call light ‘electromagnetic radiation’

6. Light as Particles
We can think of light, acting as a particle, as a photon (or particle of light)
The photon is massless, and travels at the speed of light (2.998x108 m/s)

7. Heisenberg Uncertainty Principle
It is impossible to know the position and momentum of subatomic particles simultaneously

8. Electromagnetic Radiation
Raging Martians Invaded Venus Using X-Ray Guns
Ronald McDonald Is a Very Ugly eXceptional Guy

9. Parts of a Wave Amplitude (A) – height of a wave
Wavelength (λ) – how long the wave is (distance between crests)
Crest – top part of a wave
Trough – bottom of a wave
Frequency (ν) – how many wavelengths pass through a point per unit time (1/s)

10. Wave Equations
The speed of a wave (for light c, c = 2.998x108 m/s) equals the wavelength times the frequency
c = λ*ν
The energy of a wave (E) equals Planck’s constant (h, h=6.626x10-34 Js) times the frequency
E = h*ν

11. Wave Equation Proportionalities
For the Equations:
c = λ*ν
Wavelength is inversely proportional to frequency
E = h*ν
Energy is proportional to frequency
E = h * c / λ
Energy is also inversely proportional to wavelength

12. Wave Equation Proportions You Try
If the energy of an electromagnetic wave decreases, what happens to the wave’s frequency?

13. If the frequency of an electromagnetic wave halves, what happens to the wave’s wavelength?
If the wavelength of an electromagnetic wave doubles, what happens to the wave’s energy?

14. You Try Wave Equations
Calculate the wavelength of yellow light (ν=5.09x1014 1/s)
Calculate the Energy of a yellow light wave
If the wavelength of an electromagnetic wave is 600 nm, what is that wave’s energy?

15. Atomic Spectra
When an electron transitions to a higher energy level, light is absorbed
When an electron transitions to a lower energy level, light is given off or transmitted

16. Emission of Light Results in Atomic Spectra

17. Rydberg Equation
Created by Johannes Rydberg who wanted to find the relationship between spectral lines in atomic spectra
Equation used to predict the wavelength of light for a given energy transition
This equation works for 1 electron elements, but not so well for multiple electron elements

18. Rydberg Equation cont’d
Rydberg noticed an interesting relationship between the energy levels of electrons and a resulting photon
RH is the Rydberg constant = … x10-7 1/m
n‘s are energy levels, where n2>n1

19. Rydberg You Try
What is the wavelength for light given an electronic transition between the 2nd and 3rd energy levels?