1. Chapter 5 Electrons In Atoms 5.3 Atomic Emission Spectra
5.1 Revising the Atomic Model
5.2 Electron Arrangement in Atoms
5.3 Atomic Emission Spectra
and the Quantum
Mechanical Model
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2. Ground state - electron occupies lowest possible energy level
Energy Levels in Atoms
Ground state - electron occupies lowest possible energy level
Excited state - electron absorbs energy and jumps to a higher energy level
When electron returns to ground state, it releases energy in the form of light
Emission
Line
Spectra
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3. Light and Atomic Emission Spectra
Light consists of electromagnetic waves.
Amplitude - wave height
Wavelength () - distance between the crests.
Frequency () - number of wave cycles to pass a given point per unit of time.
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4. Light and Atomic Emission Spectra
Speed of Light = wavelength x frequency
c =  108 m/s.
c = ln
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5. Light and Atomic Emission Spectra
Frequency () and wavelength () are inversely proportional.
As one increases the other decreases.
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6. Light and Atomic Emission Spectra
Low energy
( = 700 nm)
High energy
( = 380 nm)
Frequency  (s-1)
3 x 106
3 x 1012
3 x 1022
102
10-8
10-14
Wavelength  (m)
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7. Calculating the Wavelength of Light
Sample Problem 5.2
Calculating the Wavelength of Light
Calculate the wavelength of the yellow light emitted by a sodium lamp if the frequency of the radiation is 5.09 × 1014 Hz (5.09 × 1014/s).
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8. Sample Problem 5.2
c = ln
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9. What is the frequency of a red laser that has a wavelength of 676 nm
What is the frequency of a red laser that has a wavelength of 676 nm? Note: 1 m = 109 nm
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10. What is the frequency of a red laser that has a wavelength of 676 nm?
c = ln c 
 =
 = = = 4.43  1014 Hz
c  108 m/s
  10–7 m
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11. The Quantum Mechanical Model
Do Now
A green light has a wavelength of 5.30 x 10-7 m. Calculate the frequency of this light. c = 3.0x108 m/s
A violet light has a frequency of 7.5 x 1014 Hz. Calculate the wavelength of this light.
Convert your answer for #2 to nanometers.
1m = 109 nm
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12. The Quantum Concept and Photons
Energy
Planck assumed energy is quantized
Energy of a single quantum is proportional to the frequency of radiation emitted
h = Plank’s Constant = x J·s
E = hn
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13. Calculating the Energy of a Photon
Sample Problem 5.3
Calculating the Energy of a Photon
What is the energy of a photon of microwave radiation with a frequency of 3.20 × 1011/s?
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14. E = h  = (6.626  10–34 J·s)  (3.20  1011/s) = 2.12  10–22 J
Sample Problem 5.3
E = h  = (6.626  10–34 J·s)  (3.20  1011/s)
= 2.12  10–22 J
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15. What is the frequency of a photon whose energy is 1.166  10–17 J?
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16. What is the frequency of a photon whose energy is 1.166  10–17 J?
E = h n
n = h E
 = = =  1016 Hz
6.626  10–34 J
1.166  10–17 J·s E h
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17. END OF 5. 3 EM Waves https://www. youtube. com/watch
END OF 5.3 EM Waves Fireworks
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