1. Basic Chemistry Chapter 5 Electronic Structure and Periodic Trends
Chapter 5 Lecture
Basic Chemistry
Fifth Edition
Chapter 5 Electronic Structure and Periodic Trends
5.1 Electromagnetic Radiation
Learning Goal Compare the wavelength, frequency, and energy of electromagnetic radiation.

2. Chapter 5 Readiness
Key Math Skills
Converting between Standard Numbers and Scientific Notation (1.5)
Core Chemistry Skills
Using Prefixes (2.4)

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 1 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
“cee equals lambda nu”
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.

9. Inverse Relationship of λ and ν
The inverse relationship between 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 400 to 700 nm.

11. Electromagnetic Spectrum

12. Learning Check
Blue light, due to its shorter wavelength, is scattered more by the molecules in the atmosphere than are the 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?

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)?

16. Chemistry Link to Health
Biological Reactions to UV Light
In a type of depression called seasonal affective disorder (SAD), people experience mood swings and depression during the winter.
Some research suggests that SAD is the result of a decrease in serotonin, or an increase in melatonin, when there are fewer hours of sunlight.
One treatment for SAD is therapy using bright light provided by a lamp called a light box.