1. Modern Chemistry Chapter 4 Arrangement of Electrons in Atoms Sections 1-3 The Development of a New Atomic Model The Quantum Model of the Atom Electron Configurations

2. Section 1 The Development of a New Atomic Model

3. Section 1 Vocabulary Electromagnetic radiation Electromagnetic spectrum Wavelength Frequency Photoelectric effect Quantum Photon Ground State Excited state Line-emission spectrum Continuous spectrum

4. Properties of Light Electromagnetic Radiation: a form of energy that exhibits wavelike behavior as it travels through space. Wavelength: the distance between corresponding points on adjacent waves Frequency: the number of waves that pass a given point in a specific time.

5. Properties of a Wave: Amplitude – is the height of the wave measured from the origin to its crest.Amplitude – is the height of the wave measured from the origin to its crest. –The brightness or intensity of the light depends on the amplitude. –The greater the amplitude, the brighter the light.

6. Wavelength and Frequency Image p. 98

7. Electromagnetic Spectrum Image p. 98

8. Electromagnetic Spectrum Image p. 98

9. Properties of Light wavelength x frequency = speed of light x = c Visible Light = R O Y G B I V Long Low Low E Short High High E

10. The Photoelectric Effect Max Planck proposed that energy is proportional to the frequency of the electromagnetic wave. Electromagnetic energy is emitted from objects in small packages called quanta. E = h Planck’s constant –h = 6.626 x 10 -34 Jsec

11. Light as Particles QuantizedContinuousQuantizedContinuous

12. Quanitization of Energy Animation

13. The Photoelectric Effect Albert Einstein expanded on Planck’s idea. Electromagnetic radiation has a dual wave-particle nature. A particle of light is a photon. Photon: a particle of electromagnetic radiation having zero mass and carrying a quantum of energy. E photon = h

14. Energy of a Photon Animation p. 98

15. The Photoelectric Effect The photoelectric effect refers to the emission of electrons from a metal when light shines on the metal. p. 99

16. Photoelectric Effect Animaiton

18. The Photoelectric Effect To knock an electron loose, it must be hit with a photon which possesses a minimum amount of energy. This energy corresponds to its frequency. Different metals hold electrons more or less tightly So different metals require different frequencies to show the photoelectric effect.

19. The H-Atom’s Line Emission Spectrum Electric current is passed through a vacuum tube with hydrogen in it. A glow is produced When shined through a prism a line emission spectrum is produced p. 101

20. Absorption and Emission Spectrum Animation

21. Bohr Model of the Atom Niels Bohr proposed orbits for the electrons Each orbit has a fixed energy Lower energy orbits are closer to the nucleus Between orbits the electron cannot exist

22. Explaining the Line Emission Spectrum An electron absorbs a specific amount of energy (absorption) and moves from its ground state to an excited state

23. Explaining the Line Emission Spectrum The electron returns to its ground state and emits a photon (emission).

24. Explaining the Line Emission Spectrum This photon has an energy corresponding to the difference between the two states. This photon has a specific E, , and color.

25. Photon Emission and Absorption Image p. 102

26. Bohr Model of the Atom Bohr’s calculated values for the lines agreed with the values observed for the lines in each series. However, it did not explain the spectra of atoms with more than one electron.

27. Bohr Model of the Atom Animation

28. Bohr and Einstein