# Electromagnetic Radiation and the Bohr Model of the Atom - PowerPoint PPT Presentation

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## Electromagnetic Radiation and the Bohr Model of the Atom

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### Electromagnetic Radiation and the Bohr Model of the Atom Objective: Students will understand the Bohr model of the atom by understanding light. – PowerPoint PPT presentation

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Title: Electromagnetic Radiation and the Bohr Model of the Atom

1
Electromagnetic Radiation and the Bohr Model of
the Atom
• Objective Students will understand the Bohr
model of the atom by understanding light.

2
Review Rutherfords Model
3
Rutherfords Contributions
• 1. He discovered the nucleus
• 2. Found atom to be mostly empty space.
• 3. Knew that the Electrons went around the atom

4
Rutherfords Failure
• He couldnt explain why the negative electrons
arent attracted into the positive nucleus,
causing the atom to collapse.
es/wavpart2.html

5
Neils Bohr
Anyone who isnt shocked by quantum theory
doesnt understand it.
6
What are the components of a wave?
• A wave has frequency and wavelength

7
Frequency
• The of peaks that pass by in a given amount of
time
• Hz 1/sec
• MHz 1,000,000/sec
• KHz 1,000/sec

8
• Name Several Types of electromagnetic

9
How do waves differ?
• They have different wavelengths
• They have different frequencies
• They have different energies

10
How are they different?
• They have different frequencies
• They also have different energies

Then here to see how they are the same!
11
What do they all have in common?
• They all travel at the speed of light
• 3.00 x 108 meter/sec

12
Wavelength and Frequency
• If the ? 2 meters and ? 10/sec, find the
speed
• ? x ? speed
• 2 meters x 10/sec 20.0 meters/sec
• 5 meters x ______ 20.0 meters/sec
• So frequency and wavelength are inversely
proportional

13
• KSL broadcasts at 1160 KHz. Find the ? of KSLs
signal.
• 1160KHz 1160000 /sec
• Wavelength x frequency speed
• ? x 1160000 3.0 x108 m/sec
• (3.0 x108 m/sec)/(1160000/sec) 258 meters

14
What is a Photon
• Photons are light particles. A bundle of energy

15
Energy of Photons
• The energy of a photon is given by this equation
E ? h.
• The symbol h represents Plancks constant. It
has a value of

16
KSL 1160
• Find the Energy of a photon of light produced by
KSL (1160 KHz)
• E ? h
• E 1160000 s-1 x 6.626 x 10-34 Js
• E 7.69 x 10-28 J

17
Energy and Frequency
• How are Energy and ? related?
• The higher the frequency the greater the energy.
• How are Energy and ? related?
• The lower the energy the longer the ?

18
• Turn your book to page 325. What is the
electromagnetic with the lowest energy?

19
Who or what is Roy G Biv?
• An acronym for the colors of the rainbow. It is
not a person.

20
Hydrogen and Roy G Biv
• The colors emitted when energy is passed through
hydrogen is

21
The Quantum Atom
• Atoms are quantized because they only emit light
at certain frequencies and energies.
• A Quantum is the smallest quantity of radiant
energy.

22
(No Transcript)
23
A Staircase Not a Ramp
• Look at pg 330 Figure 11.15. Like a staircase,
the atom has specific energies. A ramp has
infinitely small divisions.

24
What Does N represent?
• The Energy Levels inside the atom

25
What values can N have
• 1, 2, 3, .
• In the hydrogen atom, where does the electron
reside?
• In the lowest energy level or n1
• The electron can move up to higher energy levels
by absorbing photons.
• We then say the electron is excited

26
A relaxing electron
• What happens when an electron relaxes?
• It falls from a high energy level to a lower one.
• What happens to the extra energy?
• It is emitted in the form of light.
• The further an electron falls the more energy it
gives off

27
What Gives off the Most Energy?
Higher Energy
Lower Energy
28
Finding the energy of n3
• The equation to find the energy of the hydrogen
energy levels is
• E -2.178 x 10-18 J (1/N2)
• E -2.178 x 10-18 J (1/32)
• E -2.42 x 10-19 J

29
Finding the difference between n2 and n3
• For N2, E -5.45 x 10-19 J
• For N3, E -2.42 x 10-19 J
• What happens if an electron falls from N3 to
N2?
• Just take n2 and subtract n3, that gives you ?E
• ?E 3.0 x 10-19 J

30
Calculate the ?
• E ? h
• 3.03 x 10-19 J ? h
• 3.03 x 10-19 J ? x 6.626 x 10-34Js
• ? 4.57x 1014 Hz
• ? x ? 3.03 x 108 meters/sec
• ? x 4.57x 1014 3.0 x 108 meters/sec
• ? 6.56 x 10-7 meters

31
The Lyman and Balmer series
• If an electron falls to n1, the energy is to
high for us to see.
• It can be detected but it falls into the UV
spectrum

32
Ultra Violet, Infra Red, Visible
• Where the electron falls to determines the type
of light it produces.
• If it falls to the n3, it produces IR.
• We can only se it if it falls to the n2

33
The absorption Spectrum
34
Quiz 1
• 1. What was the shortcoming of the Rutherford
model of the atom?
• a. It couldnt explain how the electron stayed in
orbit.
• b. It couldnt explain the existence of
electrons.
• c. It couldnt explain the existence of protons.

35
• 2. Who improved the Rutherford model?
• a. Dalton
• b. JJ Thompsonc. Neils Bohr
• d. Max Plank

36
• 3. Who is the constant h named after?
• a. Dalton
• b. JJ Thompsonc. Neils Bohr
• d. Max Plank

37
• 4. Which has the longest wavelength?
• a. Red Light
• b. UV Lightc. IR Light
• d. Violet Light

38
• 5. Which form of electromagnetic energy has the
most energy?
• a. Red Light
• b. UV Lightc. IR Light
• d. Violet Light

39
• 6. Which elements spectrum did Bohr explain?
• a. Helium
• b. Hydrogenc. Carbon
• d. Oxygen

40
• 7. Which has the lowest energy in the visible
spectrum?
• a. Red Light
• b. UV Lightc. IR Light
• d. Violet Light

41
• 8. Who found energy levels in the atom?
• a. Dalton
• b. JJ Thompsonc. Neils Bohr
• d. Max Plank

42
• 9. W?
• a.
• b. c.
• d.

43
• 10. Which electronic transition gives off the
most energy in the hydrogen atom?
• a. N2 to N1
• b. N3 to N2c. N4 to N3
• d. N4 to N2