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Charles Hakes Fort Lewis College 1
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Chapter 2 Spectroscopy / Review Charles Hakes Fort Lewis College 2
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Outline Test Wednesday Spectroscopy Check posted grades! Charles Hakes
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Misc If you received a C- or below (or any grade you have questions about) for your mid-term grade, please come by my office to discuss your situation. Charles Hakes Fort Lewis College 4
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Lab notes No Inside lab this week
Constellation presentations soon. This is an individual lab. Picture How to find it Interesting objects History/Mythology Participation Charles Hakes Fort Lewis College 5
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Lab notes Report Lab options. This is a group lab.
Track the Sunset (Sunrise) Track the Moonrise (Moonset) Track the motion of (Mars, Jupiter, Saturn) against the background stars Track the moons of Jupiter (Saturn) Track sunspots Dark Sky star count Other labs that you think up Charles Hakes Fort Lewis College 6
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Test Topics Chapter 0 - review Chapter 1 - review, and add
1.3 Kepler 1.4 Newton Chapter 2 - review, and add 2.4 Blackbody radiation 2.5 Spectroscopy Chapter 4 - The Solar System 4.1 inventory (review general properties) 4.2 debris (asteroids, meteoroids, comets) 4.3 solar system formation (nebular theory) Charles Hakes Fort Lewis College 7
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Test Topics Chapter 5 - Earth and Moon Chapter 6 - Terrestrial Planets
Entire chapter (particularly atmospheres) Chapter 6 - Terrestrial Planets 6.3 and 6.8 atmospheres (supplement to 5.3) Other sections - just a quick read, on your own. Chapter 7 - just a quick read, on your own. Review questions on-line Charles Hakes Fort Lewis College 8
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Photon energy The energy of a photon (a packet of light) is directly proportional to the frequency of the photon. High frequency means high energy Double the frequency means double the energy of the photon. Charles Hakes Fort Lewis College 9
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Figure 2.10 Blackbody Curves
Note the logarithmic temperature scale. For linear scale, go look at the “black body” section of: example - oven Charles Hakes Fort Lewis College 10
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Stefan’s Law Total energy radiated (from each m2 of surface area) is proportional to the fourth power of the temperature (T)4. And the Stefan-Boltzmann equation: F = sT4 (here F is Energy Flux) Charles Hakes Fort Lewis College 11
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Small Group Exercise recall: F = sT4
A pulsating variable star has a temperature ranging from 4000 K to 8000 K. When it is hottest, each m2 of surface radiates how much more energy? recall: F = sT4 Charles Hakes Fort Lewis College 12
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When it is hottest, each m2 of surface radiates how much more energy?
A pulsating variable star has a temperature ranging from 4000 K to 8000 K. When it is hottest, each m2 of surface radiates how much more energy? A) (sqrt2)x more B) 2x more C) 4x more D) 16x more Charles Hakes Fort Lewis College 13
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When it is hottest, each m2 of surface radiates how much more energy?
A pulsating variable star has a temperature ranging from 4000 K to 8000 K. When it is hottest, each m2 of surface radiates how much more energy? A) (sqrt2)x more B) 2x more C) 4x more D) 16x more Charles Hakes Fort Lewis College 14
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Group Activity You have just baked a cake at 175C, and a Pizza at 220C. How much more energy is radiated from the Pizza? Charles Hakes Fort Lewis College 15
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Group Activity You have just baked a cake at 175C, and a Pizza at 220C. How much more energy is radiated from the Pizza? convert from C to K Charles Hakes Fort Lewis College 16
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Group Activity You have just baked a cake at 175C, and a Pizza at 220C. How much more energy is radiated from the Pizza? convert from C to K use Stefan’s Law F=sT4 Charles Hakes Fort Lewis College 17
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Group Activity You have just baked a cake at 175C, and a Pizza at 220C. How much more energy is radiated from the Pizza? convert from C to K use Stefan’s Law F=sT4 compare values using a ratio (pizza/cake) Charles Hakes Fort Lewis College 18
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How much more energy is radiated by the pizza at 220K than the cake at 175K?
A) 1.11x more B) 1.26x more C) 1.47x more D) 16x more Charles Hakes Fort Lewis College 19
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How much more energy is radiated by the pizza at 220K than the cake at 175K?
A) 1.11x more B) 1.26x more C) 1.47x more D) 16x more Charles Hakes Fort Lewis College 20
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Spectroscopy Charles Hakes Fort Lewis College 21
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ROY G BIV Charles Hakes Fort Lewis College 22
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ROY G BIV red orange yellow green blue indigo violet Charles Hakes
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Figure 2.11 Spectroscope Charles Hakes Fort Lewis College 24
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Figure 2.12 Emission Spectrum
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Figure 2.15 Absorption Spectrum
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Figure 2.16 Kirchhoff’s Laws
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Figure 2.13 Elemental Emission
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Figure 2.14 Solar Spectrum Charles Hakes Fort Lewis College 29
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But where do those lines come from?
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Background At the end of the 19th century, many scientists believed that they had “discovered it all” and that only details remained to be filled in. (Like why are those spectral lines there.) Electromagnetic energy appears to come in “packets”, called photons. Particle nature of photons helps explain interactions with matter. Photon energy is directly proportional to frequency. Charles Hakes Fort Lewis College 31
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Quantum Mechanics (How to build an atom)
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How to Build an Atom Components
Proton - heavy, positive charge Neutron - heavy, no charge Electron - light, negative charge Number of protons defines element type (atomic number) Sum of protons and neutrons defines atomic weight Charles Hakes Fort Lewis College 33
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How to Build an Atom Almost all atom mass is in the nucleus (protons and neutrons) Protons are held together by nuclear force. (Very strong, but very short range.) Protons (positive charge) make an “electromagnetic potential well.” (Attracts negative charges.) Electrons (negative charge) are attracted to the well and “fill it up” until you end up with a neutral atom. Charles Hakes Fort Lewis College 34
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Figure 2.18 Modern Atom - note electron “cloud”
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Some Rules for Atoms No two electrons can be in the same state of the same atom at the same time. Only certain energy levels are allowed. Only photons with the same energy as the difference between allowed atomic states can be absorbed or emitted from an atom. Charles Hakes Fort Lewis College 36
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Hydrogen Spectrum Transitions from excited state to ground state will emit ultraviolet light. Transitions from higher excited state to first excited state emit visible photons. Charles Hakes Fort Lewis College 37
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Figure 2.19 Atomic Excitation
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Figure 2.20 Helium and Carbon
Allowed energy levels are much more complex when multiple electrons are involved. Allowed energy levels are much more complex when multiple nuclei are involved (molecules). Charles Hakes Fort Lewis College 43
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Figure 2.21 Hydrogen Spectra - molecular and atomic
Atomic spectrum shows the Balmer lines (the “H” lines) - Ha, Hb, Hg, etc. Charles Hakes Fort Lewis College 44
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Review Questions Charles Hakes Fort Lewis College 45
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The biggest contributors to global warming are:
A) Water vapor and carbon dioxide B) Methane and carbon monoxide C) Chlorofluorocarbons (CFCs), which destroy the ozone layer D) Argon and Helium E) Al Gore and Rush Limbaugh Charles Hakes Fort Lewis College 46
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The biggest contributors to global warming are:
A) Water vapor and carbon dioxide B) Methane and carbon monoxide C) Chlorofluorocarbons (CFCs), which destroy the ozone layer D) Argon and Helium E) Al Gore and Rush Limbaugh Charles Hakes Fort Lewis College 47
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Which is correct A) wavelength * frequency = period
B) wavelength * velocity = frequency C) wavelength / velocity = frequency D) wavelength / velocity = period Charles Hakes Fort Lewis College 48
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Which is correct A) wavelength * frequency = period
B) wavelength * velocity = frequency C) wavelength / velocity = frequency D) wavelength / velocity = period Charles Hakes Fort Lewis College 49
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A) infrared, ultraviolet, gamma, radio
Which list is in the correct order of electromagnetic radiation wavelength, going from shortest to longest? A) infrared, ultraviolet, gamma, radio B) gamma, x-ray, ultraviolet, visible C) radio, infrared, visible, ultraviolet D) radio, x-ray, ultraviolet, visible E) red, violet, blue, green Charles Hakes Fort Lewis College 50
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A) infrared, ultraviolet, gamma, radio
Which list is in the correct order of electromagnetic radiation wavelength, going from shortest to longest? A) infrared, ultraviolet, gamma, radio B) gamma, x-ray, ultraviolet, visible C) radio, infrared, visible, ultraviolet D) radio, x-ray, ultraviolet, visible E) red, violet, blue, green Charles Hakes Fort Lewis College 51
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Three Minute Paper Write 1-3 sentences.
What was the most important thing you learned today? What questions do you still have about today’s topics? Charles Hakes Fort Lewis College 52
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