© 2014 Pearson Education, Inc. Chapter 5 Lecture Basic Chemistry Fourth Edition Chapter 5 Electronic Structure and Periodic Trends 5.1 Electromagnetic Radiation Learning Goal Compare the wavelength of radiation with its frequency.

© 2014 Pearson Education, Inc. Chapter Readiness Key Math Skills Solving Equations (1.4D) Core Chemistry Skills Using Prefixes (2.5)

© 2014 Pearson Education, Inc. 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.

© 2014 Pearson Education, Inc. 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 Wave Trough Wavelength, λ (lambda)

© 2014 Pearson Education, Inc. Wavelength and Frequency

© 2014 Pearson Education, Inc. 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 × 10 8 m/s.

© 2014 Pearson Education, Inc. 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 × 10 8 m/s = wavelength (λ) × frequency (ν) = wavelength (m) × frequency (s −1 )

© 2014 Pearson Education, Inc. 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.

© 2014 Pearson Education, Inc. 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

© 2014 Pearson Education, Inc. 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.

© 2014 Pearson Education, Inc. Electromagnetic Spectrum

© 2014 Pearson Education, Inc. 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? 400 nm 700 nm

© 2014 Pearson Education, Inc. 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.

© 2014 Pearson Education, Inc. Learning Check If the frequency of blue light is 6.3 × Hz, what is its frequency in kilohertz (kHz) and in megahertz (MHz)?

© 2014 Pearson Education, Inc. Solution If the frequency of blue light is 6.3 × Hz, what is its frequency in kilohertz (kHz) and in megahertz (MHz)?