1. Chapter 5 Electronic Structure and Periodic Trends
5.1 Electromagnetic Radiation
Learning Goal Compare the wavelength of radiation with its frequency.

2. Chapter Readiness
Key Math Skills
Solving Equations (1.4D)
Core Chemistry Skills
Using Prefixes (2.5)

3. Electromagnetic Radiation
We experience electromagnetic radiation when we
listen to a radio
use a microwave oven
see colors in a rainbow
have an X-ray taken
All types of electromagnetic radiation, including light, consist of particles that move as waves of energy.

4. Wavelength and Frequency
Waves of electromagnetic radiation are similar to waves you might see at the beach. The highest part of the wave is called a crest, and the lowest point is called a trough.
Wave Crest
Wavelength, λ (lambda)
Wave Trough

5. Wavelength and Frequency

6. Wavelength and Frequency
Frequency (symbol ν, nu)
is the number of times the crests of a wave pass a point in one second
is measured in hertz (Hz), equal to cycles/second or s−1
All electromagnetic radiation travels at the speed of light (c), 3.00 × 108 m/s.

7. Wave Equation
The wave equation expresses the relationship of the speed of light (m/s) to wavelength (m) and frequency (s−1). c = λν Speed of light (c) = 3.00 × 108 m/s = wavelength (λ) × frequency (ν) = wavelength (m) × frequency (s−1)

8. Electromagnetic Spectrum
The electromagnetic spectrum is an arrangement of different types of radiation from the longest to the shortest wavelength. As the wavelength increases, the frequency decreases. The speed of light (c) is constant. λ

9. Inverse Relationship of λ and ν
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

10. Electromagnetic Spectrum
The longer wavelengths include radio waves and those from cellular phones, while shorter wavelengths are produced from infrared lights, ultraviolet light, and heat lamps. Visible light ranges from 700 to 400 nm.

11. Electromagnetic Spectrum

12. Learning Check
Short wavelengths of 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 450 nm, is the wavelength of red light greater or less than 450 nm?
700 nm
400 nm

13. Solution
The wavelength of red light is greater than that of blue light, which means that the wavelength of red light is greater than 450 nm.

14. Learning Check
If the frequency of blue light is 6.3 × 1014 Hz, what is its frequency in kilohertz (kHz) and in megahertz (MHz)?

15. Solution
If the frequency of blue light is 6.3 × 1014 Hz, what is its frequency in kilohertz (kHz) and in megahertz (MHz)?