1. Chapter 9 Electronic Structure and Periodic Trends
9.1
Electromagnetic Radiation
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2. Electromagnetic Radiation
Is energy that travels as waves through space.
Is described in terms of wavelength and frequency.
Moves at the speed of light in a vacuum.
speed of light = 3.0 x 108 m/s
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3. Wavelength Wavelength (, lamda)
Is the distance between the top of a wave to the top of the next wave.
Is expressed in meters (m).
Copyright © by Pearson Education, Inc.
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4. Frequency Frequency (, nu)
Is the number of waves that pass by each second.
Is expressed in cycles per sec = cycles/s = (s-1)
Also uses hertz (Hz) = one wave/s = 1 s-1
Copyright © by Pearson Education, Inc.
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5. Inverse Relationship of  and 
The inverse relationship of wavelength and
frequency means that
Longer wavelengths have lower frequencies.
Shorter wavelengths have higher frequencies.
Different types of electromagnetic radiation have different wavelengths and frequencies.
 = c = 3.0 x 108 m/s
 
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6. Learning Check
The short wavelengths of the color blue are dispersed more by the molecules in the atmosphere than longer wavelengths of visible light, which is why we say the sky is blue.
If blue light has a wavelength of 475 nm, what is its frequency?
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7. Solution Solve the wavelength expression for frequency.  = c  = c
 
Substitute in speed of light and wavelength in meters (m).
475 nm x m = x 10-7 m
1 x 109 nm
 = 3.0 x 108 m/s = x 1014 s-1
4.75 x 10-7 m
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8. Electromagnetic Spectrum
The electromagnetic spectrum
Arranges forms of energy from lower to higher.
Arranges energy from longer to shorter wavelengths.
Shows visible light with wavelengths from nm.
Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings
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9. Learning Check 1. Which of the following has the shortest wavelength?
A. microwaves B. blue light C. UV light
2. Which of the following has the lowest energy?
A. red light B. blue light C. green light
3. Which of the following has the highest frequency?
A. radio waves B. infrared C. X-rays
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10. Solution 1. Which of the following has the shortest wavelength?
C. UV light
2. Which of the following has the lowest energy?
A. red light
3. Which of the following has the highest frequency?
C. X-rays
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