5.3 Atomic Emission Spectra and the Quantum Mechanical Model 1 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Chapter 5 Electrons In Atoms 5.1 Revising the Atomic Model 5.2 Electron Arrangement in Atoms 5.3 Atomic Emission Spectra and the Quantum Mechanical Model

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 2 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. The Nature of Light Light consists of electromagnetic waves. Amplitude - wave’s height from zero to the crest. Wavelength ( ) - distance between the crests. Frequency ( ) - number of wave cycles to pass a given point per unit of time. Light and Atomic Emission Spectra

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 3 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Speed of Light = wavelength x frequency c =  10 8 m/s. c = Light and Atomic Emission Spectra The Nature of Light

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 4 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Frequency ( ) and wavelength ( ) are inversely proportional. As wavelength increases, frequency decreases. Light and Atomic Emission Spectra

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 5 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 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 × Hz (5.09 × /s).

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 6 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Sample Problem 5.2 c =

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 7 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. What is the frequency of a red laser that has a wavelength of 676 nm?

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 8 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. What is the frequency of a red laser that has a wavelength of 676 nm? c = = = = 4.43  m c  10 8 m/s 6.76  10 –7 /s c =

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 9 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Light and Atomic Emission Spectra The Nature of Light When sunlight passes through a prism, different wavelengths separate into a spectrum of colors. -Red has the longest wavelength and lowest frequency. -Violet has the shortest wavelength (highest frequency)

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 10 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Light and Atomic Emission Spectra Wavelength (m) Low energy ( = 700 nm) High energy ( = 380 nm) Frequency (s -1 ) 3 x x x

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 11 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Light and Atomic Emission Spectra

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 12 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. The amount of radiant energy (E) of a single quantum absorbed or emitted by a body is proportional to the frequency of radiation ( ). h = Plank’s Constant = x J·s The Quantization of Energy E = h The Quantum Concept and Photons

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 13 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Photoelectric effect: electrons are ejected when light of sufficient frequency shines on a metal. Light quanta are called photons Energy of a photon = E = h x ⋎ The Quantum Concept and Photons

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 14 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Calculating the Energy of a Photon What is the energy of a photon of microwave radiation with a frequency of 3.20 × /s? Sample Problem 5.3

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 15 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. E = h = (6.626  10 –34 J·s)  (3.20  /s) = 2.12  10 –22 J Sample Problem 5.3

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 16 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. What is the frequency of a photon whose energy is  10 –17 J?

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 17 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. What is the frequency of a photon whose energy is  10 –17 J? E = h == h E = = =  Hz E  10 –34 J h  10 –17 J·s

5.3 Atomic Emission Spectra and the Quantum Mechanical Model 18 > Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. END OF 5.3 EM Waves Fireworks