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ASTR101: Introduction to Astronomy

Unit 5: Matter and Light   In this unit, you will be introduced to some basic physics that is used to describe the universe.  The most obvious components of the physical universe are matter and light, though it turns out to be a bit more complicated than that.  Matter is composed of atoms, which, for our purposes, will be described by the Bohr model.  We now know that light is just part of a larger phenomenon known as electromagnetic radiation.  The physics of this unit will be the basis for the later units on the evolution of the universe from its beginning to the present.

Unit 5 Time Advisory
This unit should take approximately 13 hours to complete.

☐    Subunit 5.1: 3 hours

☐    Subunit 5.2: 1 hour

☐    Subunit 5.3: 2 hours

☐    Subunit 5.4: 2 hours

☐    Subunit 5.5: 2 hours

☐    Subunit 5.6: 1 hour

☐    Assessment: 2 hours

Unit5 Learning Outcomes
Upon successful completion of this unit, the student will be able to: - List the advances in our knowledge of the atom from the time of Democritus to the present. - Compare and contrast the Bohr model of the atom to earlier models. - Compare and contrast the differences between the wave and particle models for light and list the nineteenth-century evidence in favor of the wave model. - List the major divisions of the electromagnetic spectrum. - Compare and contrast bright-line emission spectra with dark-line absorption spectra, including the mechanism for their production according to the Bohr model of the atom.

5.1 Atoms   - Reading: The Saylor Foundation’s “Unit 5: Matter and Light” Link: The Saylor Foundation’s “Unit 5: Matter and Light” (PDF)

 Instructions: This reading provides an overview of the material we
will cover in Unit 5.  Read it carefully, but please don’t think
that you have to fix every single fact into your memory.  What you
should strive for is to be sure that it makes sense to you as you
are reading it and that when you are finished you can briefly
summarize the main points of the reading.  You should read this both
as you start and after you have finished working your way through
the unit.  

 Reading this article should take approximately 45 minutes.
  • Reading: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “Atoms and Molecules” Link: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “Atoms and Molecules” (HTML)

    Instructions: This article discusses the constituents of atoms and introduces the concept of isotopes.

    Reading this article should take approximately 5 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

5.1.1 Early Models of the Atom   - Reading: Regents Exam Prep Center: “The Rutherford Model” Link: Regents Exam Prep Center: “The Rutherford Model” (HTML)

 Instructions: This article discusses the alpha scattering
experiment Rutherford used in developing his nuclear model of the
atom.  Please read it carefully and make sure you understand how the
data supports the model.  

 Reading this article should take approximately 15 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

5.1.2 The Bohr Model of the Atom   - Web Media: YouTube: Mitchell Youngerman’s “Atomic Models Timeline Project” Link: YouTube: Mitchell Youngerman’s “Atomic Models Timeline Project” (YouTube)

 Instructions: This video discusses the people who developed various
models of the atom.  

 Watching this video should take less than 5 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Reading: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “The Bohr Model” Link: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “The Bohr Model” (HTML)

    Instructions: This article introduces you to the Bohr model and the allowed energy levels of the atom.  You should come away with the distinction between quantized energy levels and continuously allowed energies.

    Reading this article should take approximately 15 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

5.2 The Chemical Elements   - Web Media: ChemicalElements.com: Yinon Bentor’s “Online Interactive Periodic Table of the Elements” Link: ChemicalElements.com: Yinon Bentor’s  “Online Interactive Periodic Table of the Elements” (HTML)

 Instructions: At this link, you can click on an element in the
table, and information on that element will appear.  

 Reviewing this information should take approximately 10 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

5.3 Radioactive Decay   5.3.1 Types of Radioactivity   - Web Media: YouTube: mtchemers’ “Types of Radiation from Radioactive Decay” Link: YouTube: mtchemers’ “Types of Radiation from Radioactive Decay” (YouTube)

 Instructions: This is an animation that shows how an electric field
affects the three types of radiation and determines their charges.  

 Watching this video should take less than 5 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Reading: Oracle ThinkQuest: “Three Types of Radioactive Decay” Link: Oracle ThinkQuest: “Three Types of Radioactive Decay” (HTML)

    Instructions: This is a very brief description of the three types of radioactive decay.  Focus on the before and after structure of the nucleus and the nature of the emitted radiation.

    Reading this article should take approximately 10 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Reading: Oracle ThinkQuest: “World of Atom: Types of Radioactivity” Link: Oracle ThinkQuest: “World of Atom: Types of Radioactivity” (HTML)

    Instructions: Read this article to supplement the previous one.

    Reading this article should take approximately 15 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

5.3.2 Radioactive Dating   - Web Media: University of Colorado’s Physics 2000: “Isotopes and Radioactivity” Link: University of Colorado’s Physics 2000: “Isotopes and Radioactivity” (Java)

 Instructions: This is a Java applet that discusses and illustrates
half-life.  It provides animations for the decay in real time of
several short half-fife isotopes.  Try this for several different
isotopes.  Be sure to scroll down to view the graph as time
elapses.  

 Studying this resource should take approximately 15 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Reading: Brigham Young University: Grant W. Mason’s Physical Science 100: “Radioactivity and Half-Life” Link: Brigham Young University: Grant W. Mason’s Physical Science 100: “Radioactivity and Half-Life” (HTML)

    Instructions: This reading defines half-life and provides an illustrative animation.  Be sure to click on the animation.

    Studying this resource should take approximately 10 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

5.4 Electromagnetic Radiation   5.4.1 James Clerk Maxwell Electromagnetic Theory   - Reading: National Aeronautics and Space Administration: “Scientists and Electromagnetic Waves: Maxwell and Hertz” Link: National Aeronautics and Space Administration: “Scientists and Electromagnetic Waves: Maxwell and Hertz” (HTML)

 Instructions: This article is a brief description of the
contributions of Maxwell and Hertz to our understanding of
electromagnetic radiation.  

 Reading this article should take approximately 10 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

5.4.2 The Electromagnetic Spectrum   - Reading: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “The Electromagnetic Spectrum” Link: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “The Electromagnetic Spectrum” (HTML)

 Instructions: This article introduces the various regions of the
electromagnetic spectrum including the colors of the visible
spectrum.  

 Reading this article should take approximately 10 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Web Media: YouTube: Best0fScience’s “Introduction to the Electromagnetic Spectrum” Link: YouTube: Best0fScience’s “Introduction to the Electromagnetic Spectrum” (YouTube)

    Instructions: This video by the National Aeronautics and Space Administration discusses the properties of the various regions of the electromagnetic spectrum.

    Watching this video should take approximately 5 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

5.5 Atomic Spectra   5.5.1 Types of Spectra   - Reading: M. Colleen Gino’s Introduction to Solar Observing: “Different Types of Spectra” Link: M. Colleen Gino’s Introduction to Solar Observing: “Different Types of Spectra” (HTML)

 Instructions: This article gives a brief description of the three
types of spectra and the way in which they are produced.  

 Reading this article should take approximately 10 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Web Media: YouTube: Derek Owens’ Physical Science 7.3a: “The Nature of Light” Link: YouTube: Derek Owens’ Physical Science 7.3a: “The Nature of Light” (YouTube)

    Instructions: This video is mostly about emission spectra and shows the spectra of several elements.

    Watching this video should take approximately 5 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Web Media: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “The Solar Spectrum” Link: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “The Solar Spectrum” (HTML)

    Instructions: This article illustrates the dark-line spectrum of the sun.  It also illustrates the wavelength distributions of a hotter and a cooler star relative to the sun.  This explains why the surface temperature of a star determines its color.

    Reading this article should take approximately 15 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

5.5.2 Atomic Spectra and the Bohr Model of the Atom   - Reading: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “Atomic Absorption and Emission Spectra” Link: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “Atomic Absorption and Emission Spectra” (HTML)

 Instructions: This article goes over the types of spectra,
discussing the spectrum of hydrogen in some detail.  

 Reading this article should take approximately 15 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.

5.6 The Dual Nature of Electromagnetic Radiation   - Reading: InfoPlease: “The Nature of Light” Link: InfoPlease: “The Nature of Light” (HTML)

 Instructions: This article provides a brief history of our models
of light and other types of electromagnetic radiation.  It will
introduce you to the strange concept that light sometimes behaves as
if it were a wave and sometimes as if it were a stream of particles,
even though these two models are logically incompatible with one
another.  Scientists use one or the other depending on which is most
helpful in their particular application.  In most applications in
astronomy, it is easiest to think of light as a wave.  

 Reading this article should take approximately 15 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Reading: InfoPlease: “The Dual Nature of Light” Link: InfoPlease: “The Dual Nature of Light” (HTML)

    Instructions: This reading will complement the previous reading.

    Reading this article should take approximately 20 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Reading: The Saylor Foundation’s “Unit 5 Assessment” Link: The Saylor Foundation’s “Unit 5 Assessment” (PDF)

    Instructions: When you have finished the entire unit, please complete this assessment without referring to the readings.  When you are finished with the assessment, you can check your answers against the Saylor Foundation’s “Unit 5 Assessment – Answer Key” (PDF).

    Completing this assessment should take approximately 2 hours.