1. Nuclear Atom and Unanswered Questions
Rutherford
Positive charge in the middle surrounded by fast moving electrons
How come the electrons don’t get pulled into the middle?
Why do different elements behave differently?

2. Early 1900’s Scientists made some observations
Certain elements emitted visible light when heated in a flame
Elements chemical behavior is related to the arrangement of electron in its atoms
Relationship between atoms and light

3. Light Electromagnetic radiation
Form of energy that exhibits wavelike behavior as it travels through space
Ex) Visible light, microwaves, X-rays, radio waves…

4. Waves
What is a wave?
A traveling rhythmic disturbance
Carries energy from place to place without requiring matter to travel across the in-between distance
Matter does not move from one place to another, the disturbance (wave) does.
Sound and light travel in waves

5. Wave Basics Crest – the highest point above the rest position.
Trough – the lowest point below the rest position.

6. Speed of a Wave
Wavelength (λ) – the distance between a point on one wave and the same point on the next wave cycle.
Speed = Wavelength x Frequency (s=λf)
Unit = m/s (meters per second)

7. Parts of a wave
Amplitude – (A) wave height – relates to the intensity of the light
Wavelength (λ) – distance between two adjacent peaks
Frequency ( ν) – the number of wavelengths (or wave cycles) that pass a given point in one second
Hertz (Hz) – unit for frequency; a wave that sends1 crest (or 1 wave cycle) by a point every second would be ν = 1Hz or “1/ s”
Velocity – speed of light = c = 3.00x108m/s

8. Amplitude Example
The more energy a wave has, the greater is its amplitude.

9. The Waves of the Spectrum
The full range of frequencies of electromagnetic radiation is called the Electromagnetic Spectrum.

10. Visible Light
Visible light is light is the part of the EM spectrum the human eye can see.
Each color corresponds to a specific frequency and wavelength.

11. Complete the worksheet while watching the movie.

12. Homework Book Questions
Read, notes, and vocabulary for 6.2
6.9, 6.13, 6.15, 6.17, 6.18
Due Monday

13. Visible Light Small part of the electromagnetic spectrum
Short wavelengths bend more than long wavelengths as they pass through the prism
Results in the rainbow we see (ROY G BIV)
Energy increases with increasing frequency

14. Practice Which of the below waves has … the higher frequency?
the longer wavelength?
If one wave represented red light and one represented blue light which would be which?
Which one would have more energy???

15. EM Spectrum
Bigger slower to shorter faster (more harmful)

16. Wave speed
Speed, frequency and wavelength are related and give us an understanding of the energy of the wave!!!
speed of light = frequency x wavelength
c (in meter/second) = ν (in hertz) x λ (in meters)
c = v x λ

17. Practices problems
Red light has a wavelength of 722nm, what is the frequency of the light?
Don’t forget to convert nm to m.
An electromagnetic wave is measured to have a frequency of 4.7x1013Hz. Calculate its wavelength and identify the type of wave.

18. Things wave model of light cannot explain
Black-Body radiation
Emission of light from hot objects
2) Photoelectric effect
Emission of electrons from metal surfaces on which light shines
3) Emission line spectra
- Emission of light from electronically excited gases
i.e. tungsten metal emits bright
white light when heated
i.e. red glow of electric stove
burner

19. Quantum Concept
Max Planck said energy can be either released or absorbed by atoms ONLY in discrete “chunks” of some minimum energy
Quantum meaning “fixed amount” is the smallest quantity of energy that can be emitted or absorbed as electromagnetic radiation

20. Quantum Concept
The ball can only have certain amounts of potential energy when at rest.
The potential energy of the ball at rest is quantized.

21. Like a set of stairs, the energy states of an electron is quantized – i.e. electrons are only found on a specific step
The ramp is an example of a continuous situation in which any energy state is possible up the ramp

22. Einstein used quantum theory to explain photoelectric effect.
Photocell - emitted electrons are drawn toward positive terminal creating an electrical circuit
When photons of significant high energy strike a metal surface – electrons are emitted from the metal

23. Energy of quantum = Planck’s constant x frequency
Quantum Concept
Planck proposed that the energy (E) of a single quantum is equal to a constant (Planck’s constant (h)) times the frequency of the radiation.
Planck’s constant = h = 6.626x10-34 Joule-second (Js)
Energy of quantum = Planck’s constant x frequency
E = h v

24. Practice Exercises
A laser emits light with a frequency of 4.69x1014 s-1. How much energy is emitted from one quantum of the radiation from this laser?
Calculate the energy of one photon (quantum) of yellow light whose wavelength is 589nm.

25. Matter can only gain or lose energy in small specific amounts. Quantum
Minimum amount of energy that can be gained or lost by an atom.

26. Homework Book Questions
Read, notes, and vocabulary for 6.2
6.9, 6.13, 6.15, 6.17, 6.18

27. Quantum Concept Glowing light emitted by hot objects
As the object is heated it gains energy…
As the object gains it changes colors (emits different colors)

28. EM Spectrum Drawing Where is red in the rainbow? Why?
Where is violet in rainbow? Why?
Pick something to draw.
You are given the wavelengths of each color (on sheet)
Determine a scale that you are going to use to draw
Convert nm to mm
Convert wavelengths of each color to frequency
Convert frequency to energy (think Planck)
All work must be shown on back to receive credit

29. Planck Proposed that emitted light was quantized
Energy of a quantum is related to the frequency of the emitted radiation
E (quantum) = h v
E=energy
H= planck’s constant
V= frequency

30. Wave or Particle?
Electromagnetic radiation behaves sometimes like a wave and sometimes like a stream of particles.

31. Photoelectric Effect Beam of light has many wave like characteristics…
It can also be thought of as stream of tiny particles or bundles of energy
Photons
Particle of electromagnetic radiation with no mass that carries a quantum of enrgy
E (photon) = h v

32. Atomic Emission Spectrum
Set of frequencies of the electromagnetic waves emitted by the atoms of the element
Each element’s atomic emission spectrum is unique
Used to determine unknowns (forensics)

33. 5.1 Worksheet
Complete 5.1 worksheet using only your notes.

34. Interactions of Light
When light strikes a new medium, the light can be reflected, absorbed, or transmitted.
When light is transmitted, it can be refracted, polarized, or scattered.