1 Light Tools Building and confirming tools for inquiry How?Why?

2 Think with me Why do you see colors when some chemicals are flamed? Why do different chemicals => different colors? Assertion I: (proposed model): unlike planets, electrons are only allowed discrete energies* Assertion II: Energies that don’t take an electron to an allowed place are ignored by it *If the earth should stop revolving, Spinning slow enough to die... --IF, David Gates (Bread)

3 Hydrogen Atom Simulator (Dan Damelin) Also in Further Explorations (on course website) Predict: what happens to an arbitrary-energy photon? (on the slide bar labled ‘Photon Energy’ these are 10, 11, 12 & 13) Predict: what happens to an arbitrary-energy photon? (on the slide bar labled ‘Photon Energy’ these are 10, 11, 12 & 13) Predict: what happens to one that matches a difference between current & potential orbital? ((on the slide bar labled ‘Photon Energy’ these are 10.20, 12.09, etc.) Predict: what happens to one that matches a difference between current & potential orbital? ((on the slide bar labled ‘Photon Energy’ these are 10.20, 12.09, etc.) Set ‘pause mode’ to on

What is ‘ color ’ Is there a difference between your shirt and a neon light?

How does the ‘Atom Simulator’ help us understand…

6 Tool using

7 How are these different? Using a thermometer to test temperature pointing stick at sky, say magic words, wait for rain using ‘pH paper’ to count ‘protons’ using the Ba(OH) 2 ‘test for’ carbon dioxide counting geigs with a Geiger counter believing in ‘global climate change’ Any sufficiently advanced technology is indistinguishable from magic. --Arthur C. Clarke

Capturing CO2 H 2 O + CO 2 -> H 2 CO 3 H 2 CO 3 -> HCO 3 – -> CO 3 2– CO 3 2– + Ba 2+ ->BaCO 3 (white ppt.)

9 Rankings Empirical--you saw it, touched it, etc. Reasoned argument from documented/identified assumptions & previous knowledge Repeatedly established by others Never : assertions by authority regardless of the nature (or volume) of that authority

10 Principles of spectrophotometry

11 Driving Ms. Spec Set for infinite absorbance (blocked path) Set wavelength Set zero absorbance **Appendix D also reviews how to use this Spec

12 SEE for yourself! We’ll have tubes with chalk or filter paper; drop these in the specs Look at the beam (far red may be hard to see) slowly and carefully move the wavelength selector Look again Reset spec to wavelength indicated by tape on spec

13 Evaluating your expectations Graph paper pp. J-13 to 20 Predict: how will a blue liquid absorb? A green one?

14 To your specs! Tubes in the rack Find the absorbance of each color at each wavelength (record – Appendix I has tables) MOVE your body to the next wavelength (the next spec) Protocol for chlorophyll on 11-3

15 Data BlueVioletRedGreenYellowleaf This should take 15’.

16 Graphing Create a graph, table for HW See rubric!!!

17 FYI: Dye Structures Crystal Violet Yellow Napthol Green FDC Blue1 FDC Red 3 FDC Yellow5

18 The Joy of Dilution What fraction of molecules would you have to remove for there to be 1/2 as many collisions between beam & dye? OK, build a solution with 1/4 absorbance of stock; confirm Tubes will be covered

19 Photosynthesis “…converting light energy into chemical energy in the C-C & C-H bonds of sugar.”* * Freeman – fourth edition

Photosynthesis 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Light

21 Photosynthesis: Intro

22 Fashioning an assay Using the oxygen that plants belch out

23 Deflating, inflating a leaf How can you tell if photosynthesis is happening? What are the inputs? The products? How can you test for these?

24 What’s in a leaf Predict: what will we find when we grind up a leaf? Protocol: p Graph absorption of spinach extract ‘ultra’-violet light it (high or low energy)? Note!! These wavelengths re-do your DNA!!

Looking at a leaf, what would you hypothesize would be the most effective wavelengths for photosynthesis? (what is your mechanism?) 25

26 Semester project!

27 Homework Table & Graph of absorbance data READ the rubric CAREFULLY! Dilution worksheet (pp & 10) Table & Graph of absorbance data READ the rubric CAREFULLY! Dilution worksheet (pp & 10)