1. Slide 1 of 38 chemistry

2. © Copyright Pearson Prentice Hall Slide 2 of 38 Physics and the Quantum Mechanical Model Neon advertising signs are formed from glass tubes bent in various shapes. An electric current passing through the gas in each glass tube makes the gas glow with its own characteristic color. You will learn why each gas glows with a specific color of light. 5.3

3. Slide 3 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Light The amplitude of a wave is the wave’s height from zero to the crest. The wavelength, represented by (the Greek letter lambda), is the distance between the crests. The frequency, represented by (the Greek letter nu), is the number of wave cycles to pass a given point per unit of time. The SI unit of cycles per second is called a hertz (Hz). 5.3

4. Slide 4 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Light The wavelength and frequency of light are inversely proportional to each other. 5.3

5. Slide 5 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Light The product of the frequency and wavelength always equals a constant (c), the speed of light. c= 2.998 x 10 8 m/s 5.3

6. Slide 6 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Light According to the wave model, light consists of electromagnetic waves. Electromagnetic radiation includes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays. All electromagnetic waves travel in a vacuum at a speed of 2.998  10 8 m/s. 5.3

7. Slide 7 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Light Sunlight consists of light with a continuous range of wavelengths and frequencies. When sunlight passes through a prism, the different frequencies separate into a spectrum of colors. In the visible spectrum, red light has the longest wavelength and the lowest frequency. 5.3

8. Slide 8 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Light The electromagnetic spectrum consists of radiation over a broad band of wavelengths. 5.3

9. © Copyright Pearson Prentice Hall SAMPLE PROBLEM Slide 9 of 38 5.1

10. © Copyright Pearson Prentice Hall SAMPLE PROBLEM Slide 10 of 38 5.1

11. © Copyright Pearson Prentice Hall SAMPLE PROBLEM Slide 11 of 38 5.1

12. © Copyright Pearson Prentice Hall SAMPLE PROBLEM Slide 12 of 38 5.1

13. © Copyright Pearson Prentice Hall Slide 13 of 38 Practice Problems for Sample Problem 5.1 Problem-Solving 5.15 Solve Problem 15 with the help of an interactive guided tutorial.

14. Slide 14 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Atomic Spectra A prism separates light into the colors it contains. When white light passes through a prism, it produces a rainbow of colors. 5.3

15. Slide 15 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Atomic Spectra When atoms absorb energy, electrons move into higher energy levels. These electrons the lose energy by emitting light when they return to lower energy levels. When light from a helium lamp passes through a prism, discrete lines are produced. 5.3

16. Slide 16 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Atomic Spectra The frequencies of light emitted by an element separate into discrete lines to give the atomic emission spectrum of the element. 5.3 Mercury Nitrogen

17. Slide 17 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Atomic emission spectrum- the discrete lines formed when atoms absorb energy, forcing electrons into higher energy levels and then lose energy by emitting light as the electrons fall to lower energy levels The light is made up of only a few specific frequencies, depending on the element Each frequency is a different color The light is emitted as electrons fall from one energy level to another, like from n=4 to n=1 They are like atomic fingerprints- every element is unique

18. Slide 18 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Examples of Atomic Emission Spectra: http://www.avogadro.co.uk/light/bohr/spectra.htm http://www.avogadro.co.uk/light/bohr/spectra.htm Spectrum for barium and hydrogen http://jersey.uoregon.edu/vlab/elements/Elements.html http://csep10.phys.utk.edu/astr162/lect/light/absorption. html

19. Slide 19 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > An Explanation of Atomic Spectra In the Bohr model, the lone electron in the hydrogen atom can have only certain specific energies. When the electron has its lowest possible energy, the atom is in its ground state. Excitation of the electron by absorbing energy raises the atom from the ground state to an excited state. (not the orbital predicted by aufbau chart) A quantum of energy in the form of light is emitted when the electron drops back to a lower energy level. 5.3

20. Slide 20 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Atomic Emission Spectra Light emitted by an electron moving from a higher to lower energy level has a frequency directly proportional to the energy change of the electron Equation describing energy change of the electron E = h x ν (h = 6.626 x 10 -34 J/s) So different energy level drops result in different frequencies (and colors) of light

21. Slide 21 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > An Explanation of Atomic Spectra The three groups of lines in the hydrogen spectrum correspond to the transition of electrons from higher energy levels to lower energy levels. 5.3

22. © Copyright Pearson Prentice Hall Slide 22 of 38 Physics and the Quantum Mechanical Model > An Explanation of Atomic Spectra Animation 6 Learn about atomic emission spectra and how neon lights work.

23. © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Slide 23 of 38 Quantum Mechanics How does quantum mechanics differ from classical mechanics? 5.3

24. Slide 24 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Quantum Mechanics Remember that both light and electrons behave as both particles and waves! Light particles are called photons. When photons hit metals, they can result in the ejection of electrons- This is the photoelectric effect We use this property to create electron microscopes, which allow for clearer images since they have smaller wavelengths than light- see page 144 5.3

25. Slide 25 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Quantum Mechanics Today, the wavelike properties of beams of electrons are useful in magnifying objects. The electrons in an electron microscope have much smaller wavelengths than visible light. This allows a much clearer enlarged image of a very small object, such as this mite. 5.3

26. © Copyright Pearson Prentice Hall Slide 26 of 38 Physics and the Quantum Mechanical Model > Quantum Mechanics Simulation 4 Simulate the photoelectric effect. Observe the results as a function of radiation frequency and intensity.

27. © Copyright Pearson Prentice Hall Slide 27 of 38 Physics and the Quantum Mechanical Model > Quantum Mechanics Classical mechanics adequately describes the motions of bodies much larger than atoms, while quantum mechanics describes the motions of subatomic particles and atoms as waves. 5.3

28. Slide 28 of 38 © Copyright Pearson Prentice Hall Physics and the Quantum Mechanical Model > Quantum Mechanics The Heisenberg uncertainty principle states that it is impossible to know exactly both the velocity and the position of a particle at the same time. This limitation is critical in dealing with small particles such as electrons. This limitation does not matter for ordinary- sized object such as cars or airplanes. 5.3

29. © Copyright Pearson Prentice Hall Slide 29 of 38 Physics and the Quantum Mechanical Model > Quantum Mechanics The Heisenberg Uncertainty Principle 5.3

30. © Copyright Pearson Prentice Hall Slide 30 of 38 Physics and the Quantum Mechanical Model > http://www.teachersdomain.org/resources/phy03 /sci/phys/fund/quantum/index.html http://www.teachersdomain.org/resources/phy03 /sci/phys/matter/quantumcafe/index.htmlhttp://www.teachersdomain.org/resources/phy03 /sci/phys/matter/quantumcafe/index.html - Quantum Cafe

31. © Copyright Pearson Prentice Hall Slide 31 of 38 5.3 Section Quiz. 1.Calculate the frequency of a radar wave with a wavelength of 125 mm. a.2.40 10 9 Hz b.2.40 10 24 Hz c.2.40 10 6 Hz d.2.40 10 2 Hz

32. © Copyright Pearson Prentice Hall Slide 32 of 38 5.3 Section Quiz. 2.The lines in the emission spectrum for an element are caused by a.the movement of electrons from lower to higher energy levels. b.the movement of electrons from higher to lower energy levels. c.the electron configuration in the ground state. d.the electron configuration of an atom.

33. © Copyright Pearson Prentice Hall Slide 33 of 38 5.3 Section Quiz. 3.Spectral lines in a series become closer together as n increases because the a.energy levels have similar values. b.energy levels become farther apart. c.atom is approaching ground state. d.electrons are being emitted at a slower rate.

34. © Copyright Pearson Prentice Hall Slide 34 of 38 Physics and the Quantum Mechanical Model > Concept Map 5 Concept Map 5 Solve the concept map with the help of an interactive guided tutorial.

35. END OF SHOW