1. The Electromagnetic Spectrum & Electromagnetic Radiation

3. What are electromagnetic waves?
Produced by the motion of electrically charged particles
Also called “electromagnetic radiation” because they radiate from electrically charged particles.

4. LIGHT
According to the wave theory, light consists of electromagnetic waves
Examples of electromagnetic radiation include:
Radiowaves
Microwaves
Infrared waves
Visible light
Ultraviolet light
X-rays
Gamma rays

5. This is the electromagnetic spectrum
R O Y G B I V

6. Properties of waves Wavelength Frequency Amplitude
Cycles / second (Hertz)

7. Wavelength Shows a long wavelength Shows a short wavelength
Measured from crest to crest
Symbol =

8. Frequency
The number of wave cycles in a given time, measured in hertz (Hz)

9. Amplitude
The wave’s height

10. The Visible Spectrum ROYGBIV Red: longer wavelength, lower frequency
Violet: shorter wavelength, higher frequency

11. Electromagnetic waves we can’t see
Microwaves
Radio waves
X-Rays
Ultraviolet Rays
Gamma Rays

12. How do we get these?

13. Those shiny electrons!
Electrons can change energy levels

14. When energy is added to an electron, it goes to a higher energy level
Eventually the electron needs to return to it’s ground state. When it does, energy is released in the form of light.

15. Atomic Spectra

16. The energy change of the electron gives off light with a specific frequency
If an electron falls to energy level 1, ultraviolet light is emitted
If an electron falls to energy level 2, visible light is emitted
If an electron falls to energy level 3, infrared light is emitted

19. Spectra for every element!

20. What’s happening? When heated, electrons enter an energized state.
Eventually, excess energy is released as a photon of light.
High energy photons correspond to short wavelength light
Low energy photons produce long wavelength light
The colors of the light (or flame) correspond to electrons of specific energies

21. Remember, a Quantum is. . .
The amount of energy needed for an electron to change energy levels

22. Draw it!

23. The Importance of the Atomic Emission Spectrum
Like a fingerprint for the element
Each element has a unique number of electrons
So the electrons move to different energy levels when they absorb energy.
When the electrons fall, they produce a spectra specific to that element

24. So, the atomic spectra can be used to identify elements!

25. Dual Personality
So far, we’ve been talking about the wave theory of light.
Einstein said that electromagnetic radiation acts like a wave AND like particles (photons)

26. A packet of energy that behaves like both a particle AND a wave
A Photon
A packet of energy that behaves like both a particle AND a wave

27. de Broglie found (with math) that particles DO behave as waves.
A golf ball, when hit, has a wavelength as it travels through the air, though very small
To observe their wavelength, particles must be very small

28. Because of Bohr and Einstein and de Broglie
Scientists say there is a
Wave-Particle Duality of Light

29. Not Just Light
This applies to all things, but it’s easier to observe in small ones

30. Heisenberg’s Uncertainty Principle
Heisenberg said that it’s impossible to know both the location and the velocity of a particle at the same time