1. The History of the Electron
When we last left the atom, this is how it looked
Mass concentrated in the nucleus
Electrons move around it
Doesn’t explain how the electrons were arranged around the nucleus
Why aren’t the negatively charged electrons pulled into the postively charged nucleus?

2. So, where did we go from here?
In the early 1900s, scientists observed certain elements emitted visible light when heated in a flame
Analysis of the emitted light revealed
Element’s chemical behavior is related to the arrangement of electrons!

3. What is visible light? Type of electromagnetic radiation
Exhibits wave-like behavior

4. What makes up a Wave?
Wavelength
Frequency
Amplitude

5. Wavelength (λ)
The distance from one point on a wave to the same point on the next wave.
Crest to Crest or Trough to Trough
Expressed in: meters, centimeters, or nanometers
Lambda

6. Wavelength and Frequency

7. Frequency (ν) waves that pass a point per second
Expressed in: Hertz (Hz)
Hz = Waves per second
1 Hz = 1/s = 1 s-1

8. Amplitude How far a wave rises or falls
Origin to Crest OR Trough to Origin

9. Waves and Energy The higher the frequency, the higher the energy
The longer the wavelength, the lower the energy

10. Electromagnetic Spectrum
What is an electromagnetic spectrum?
All of the frequencies or wavelengths of electromagnetic radiation.
Spectrum from shortest wavelength to the longest
cosmic  gamma  X-rays  ultraviolet (UV)  visible  infrared (IR)  microwave  radar  TV  Radio

11. Electromagnetic Spectrum
Red, Orange, Yellow, Green, Blue, Indigo, Violet
Remember the three L’s are on this side (Low energy, Low frequency, long wavelength)
ROY G BIV backwards

12. Let’s Practice
1) What has the longer wavelength: X-rays verses visible
2) What has the longer wavelength: gamma verses cosmic
3) What has the higher energy: infrared verses radio
4) What has the higher energy: microwave verses infrared
5) What has the highest frequency: gamma verses radio
6) What has the highest frequency: TV verses UV

13. See if you can find the humor in this:

15. Now, how do waves relate to the atom?
That brings us to Quantum Mechanics and a few more scientists

16. Line Spectra of Excited Atoms
Excited atoms emit light of only certain wavelengths
The wavelengths of emitted light depend on the element.