1. Energy Unit Learning Goal #1: Evaluate the quantum energy changes in the atom in terms of the energy contained in light emissions.

2. The Wave-like Electron Louis deBroglie The electron propagates through space as an energy wave. To understand the atom, one must understand the behavior of electromagnetic waves.

3. Wave-Particle Duality JJ Thomson won the Nobel prize for describing the electron as a particle. His son, George Thomson won the Nobel prize for describing the wave-like nature of the electron. The electron is a particle! The electron is an energy wave!

4. Electromagnetic Radiation Energy that moves through space and matter both in the form of magnetic and electric waves and in the form of a stream of particles.

5. Wave Characteristics Wavelength The distance between two consecutive wave peaks. Frequency How many wave peaks pass a certain point per given time period.

6. Photons Stream of tiny packets of energy.

7. c = C = speed of light, a constant (3.00 x 10 8 m/s) = frequency, in units of hertz (hz, sec -1 ) = wavelength, in meters Electromagnetic radiation propagates through space as a wave moving at the speed of light.

8. E = h E = Energy, in units of Joules (kg·m 2 /s 2 ) h = Planck’s constant (6.626 x 10-34 J·s) = frequency, in units of hertz (hz, sec -1 ) = frequency, in units of hertz (hz, sec -1 ) The energy (E ) of electromagnetic radiation is directly proportional to the frequency ( ) of the radiation.

9. Long Wavelength = Low Frequency = Low ENERGY Short Wavelength = High Frequency = High ENERGY Wavelength Table

10. Copyright © by McDougal Littell. All rights reserved. 10 Light has been found to have both wave and particle characteristics. The speed of light (electromagnetic radiation) can be calculated with: c = λυ c = 3.0 x 10 8 m/s

11. Copyright © by McDougal Littell. All rights reserved. 11 Different wavelengths of EM radiation carry different amounts of energy. Red light carries less energy than blue light. The longer the wavelength of light, the lower the energy of its photons. Why?

12. Copyright © by McDougal Littell. All rights reserved. 12 Ehc λ = E = energy h = Planck’s constant c = speed of light λ = wavelength

13. Copyright © by McDougal Littell. All rights reserved. 13 Emission of Energy by Atoms As the atoms release energy, we detect the photon of energy as specific colors of light Copper emits green light because it undergoes a different energy change.

14. Copyright © by McDougal Littell. All rights reserved. 14 The Energy Levels of Hydrogen Remember that different wavelengths of light carry different amounts of energy per photon. The energy contained in the photon corresponds to the change in energy that the atom experiences going from the excited to a lower state.

15. Copyright © by McDougal Littell. All rights reserved. 15 Only certain types of photons are produced...we don’t see all colors only selected colors. The energy is said to be emitted in “discrete” amounts...or only in certain “packets” or “bundles”

16. Copyright © by McDougal Littell. All rights reserved. 16 Atoms have certain discrete energy levels...energy levels are quantized...only certain values are allowed. More like fig. b

17. Copyright © by McDougal Littell. All rights reserved. 17 http://www.colorado.edu/physics/2000/quantumzone/index.html Scientists (Bohr, Planck and others) observed unique bright line spectra when an excited gas was observed through a spectroscope. How did scientists figure this out?

18. …produces all of the colors in a continuous spectrum Spectroscopic analysis of the visible spectrum…

19. …produces a “bright line” spectrum Spectroscopic analysis of the hydrogen spectrum…

21. Element Spectra

23. This produces bands of light with definite wavelengths. Electron transitions involve jumps of definite amounts of energy.

24. Electromagnetic Spectrum https://video.weber.k12.ut.us/vportal/VideoPlayer.jsp?ccsid=1F764BCADDFBCACBCC9F8E5 A066871F4:2 https://video.weber.k12.ut.us/vportal/VideoPlayer.jsp?ccsid=1F764BCADDFBCACBCC9F8E5 A066871F4:2

25. Types of electromagnetic radiation:

26. Electromagnetic Radiation (light) Consists of waves of energy and streams of particles of energy. Wave-particle nature of light Different wavelength carry different amounts of energy. Red light (longer wavelength) has less energy than blue light (shorter wavelength).

27. Radio Waves Lowest frequency and the longest wavelengths. The longest waves are several kilometers in length. The shortest ones are only millimeters long. The electric currents at "radio frequencies" (rf) are used by radio and television transmitters and receivers.

28. Microwaves Low-frequency, low-energy waves that are used for communications and cooking. Used in cell phones.

29. Infrared Given off by the human body and most other warm objects. Heat you feel from a fire or an electrical heater.

30. Visible Light The only part of the electromagnetic spectrum that our eyes can see.

31. Ultraviolet (UV) The part of the sunlight that causes sunburns. Ozone absorbs most of the UV rays.

32. X Rays Pass through soft body tissue but are stopped by harder tissue such as bone.

33. Gamma Rays The highest energy and shortest wavelengths. Can pass through most substances. They can be used for finding tiny cracks in metals. Can be used to destroy cancer cells.