IB Chemistry on Electromagnetic Spectrum and Wave particle duality

1. Electromagnetic Spectrum
Electromagnetic spectrum ranges from Radiowaves to Gamma waves.
- Form of energy
- Shorter wavelength -> Higher frequency -> Higher energy
- Longer wavelength -> Lower frequency -> Lower energy
Wavelength, λ - long 
Frequency, f
- low 
Wavelength, λ - short 
Frequency, f
Inverse relationship between- λ and f
- high 
Electromagnetic radiation
•Travel at speed of light, c = fλ -> 3.0 x 108 m/s
•Light Particle – photon have energy given by -> E = hf
•Energy photon - proportional to frequency, f
Plank constant
• proportionality constant bet energy and freq
Excellent video wave propagation
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2. Electromagnetic Wave propagation.
Electromagnetic radiation
•
•
•
Moving charges/particles through space
Oscillating wave like property of electric and magnetic field
Electric and magnetic field oscillate perpendicular to each other and perpendicular to
direction of wave propagation.
Electromagnetic radiation
Electromagnetic wave propagation
Click here to view video
Violet
λ = 410nm
f = c/λ
= 3 x 108/410 x 10-9
= 7.31 x 1014 Hz
E = hf
= 6.626 x 10-34 x 7.31 x 1014
= 4.84 x 10-19 J
Wave
Wave – wavelength and frequency
- travel at speed of light
Red
λ = 700nm
f = c/λ
= 3 x 108/700 x 10-9
= 4.28 x 1014 Hz
E = hf
= 6.626 x 10-34 x 4.28 x 1014
= 2.83 x 10-19 J

3. Electromagnetic Wave propagation.
•
•
•
Electromagnetic radiation
Moving charges/particles through space
Oscillating wave like property of electric and magnetic field
Electric and magnetic field oscillate perpendicular to each other and perpendicular to
direction of wave propagation.
Electromagnetic radiation
Electromagnetic wave propagation
Click here to view video
Wave
Wave – wavelength and frequency
- travel at speed of light
Simulation on Electromagnetic Propagation
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Click here to view simulation
Click here to view simulation

4. Electromagnetic Wave
Violet
Red
λ = 410nm
λ = 700nm
f = c/λ
= 3 x 108/410 x 10-9
= 7.31 x 1014 Hz
f = c/λ
= 3 x 108/700 x 10-9
= 4.28 x 1014 Hz
Wavelength – Distance bet two point with same phase, bet crest/troughs – unit nm
Frequency – Number of cycle/repeat per unit time (cycles in 1 second) – unit Hz
Which light wave have higher frequency, if both have same speed reaching Y same time?
Click here on excellent video red /violet wave
Violet light
X
Y
Light travel same speed
Red flippers – long λ - less frequent
Violet shoes – short λ - more frequent
Red light
Click here to view video energy photon

5. Quantum Weirdness – Is Light/electron a Wave or Particle?
Pass BIG particles through a 2 slit
Pass waves through a 2 slit
2 bands
Particle gun
Interference patterns
of many bands
Slit
Quantum particles – small particles, like electrons – Is light/electron a Wave or Particle?
Particles
Pass electron through a 2 slit
Particles /photon
•single slit – single band
•double slit – double band
Does electron
behave as
Click here to view simulation
Interference patterns
of many bands
Waves
Wave
•Crest/trough appearing
•Double slit – interference behind screen
– bright/dark bands
Conclusion
Single electron behave like particles but travel like a wave
Waves
Principle of wave–particle duality.

6. Quantum Weirdness – Is Light/electron a Wave or Particle?
Pass electron through a 2 slit
Particles
Particles/photon
•single slit – single band
•double slit – double band
Does electron
behave as
Click here to view simulation
Interference patterns
of many bands
Waves
Pass electron through a 2 slit
Particles
Waves
•Crest/trough appearing
•Double slit – interference behind screen
– bright/dark bands
Particles/photon
•single slit – single band
•double slit – double band
Does electron
behave as
Measuring /observing it
- which slit it passes through
Waves
Waves
•Crest/trough appearing
•Double slit – interference behind screen
– bright/dark bands
Conclusion
Single electron behave like particle but travel like a wave
Try to measure it.
Principle of wave–particle duality.
Wave of possibility.

7. Is light a Wave or Particle?
Photoelectric effect
Light hits metal
Electrons are release (photoelectrons)
Current measured
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Light – Shows photoelectric effect
Shine light to metal
Current measured
Is Light a Wave or Particle?
Is Light a Wave or Particle?
Wave Theory
Particle Theory
VS
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Wave Theory
•Light energy arrives continuously, regardless of freq
•Energy proportional to amplitude
•Intensity light – depends on amplitude
•Low intensity – low amplitude
•High intensity – high amplitude
Particle Theory
•Light energy comes in tiny packets -photons
•Amt energy directly proportional to frequency, E = hf
•Red light – low freq – low energy
•Blue light – high freq – high energy

8. Is light a Wave or Particle?
Light – Shows photoelectric effect
Shine light to metal
Current measured
Is Light a Particle or Wave?
Is Light a Wave or Particle?
Wave Theory
Particle Theory
VS
Click here to view video
Wave Theory
•Light energy arrives continuously, regardless of freq
•Energy proportional to amplitude
•Intensity light – depends on amplitude
•Low intensity – low amplitude
•High intensity – high amplitude
Particle Theory
•Light energy comes in tiny packets -photons
•Amt energy directly proportional to frequency, E = hf
•Red light – low freq – low energy
•Blue light – high freq – high energy
Particle Theory
Wave Theory
Colour/Frequency light
Light energy arrives
continuously,
regardless of frequency
Intensity light
Low intensity – Low amplitude
High intensity –High amplitude
Colour/Frequency light
Red light
Low frequency – Low energy
Colour/Frequency light
Blue light
High frequency – High energy

9. Is light a Wave or Particle?
Is Light a Wave or Particle?
Wave Theory
Particle Theory
VS
Click here to view video
Colour/Frequency light
Colour/Frequency light
Intensity light
If light is Wave
• Colour/Intensity of light NOT important !
• Regardless of colour/freq/intensity
Colour/Frequency light
If light is Particle
• Colour/Frequency of light is important !
Shine RED light
Shine BLUE light
Shine light LONG enough
Red light
Low freq – Low energy
Blue light
High freq – High energy
No electrons released
Electrons are released
Are electrons released?
No electrons released
Result!

10. Is light a Wave or Particle?
Is Light a Wave or Particle?
Stream of light
Stream of photon
Fixed amt of energy – E = hf
Is Light a Wave or Particle?
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Is Light a Wave or Particle?
Video Is Light a Wave or Particle?
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Click here wave and particle
Click here wave and particle
Click here wave and particle