02 Matter Is Atoms That Move After Class

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This is lecture 2, about the atomic nature of matter and Brownian motion.

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02 Matter Is Atoms That Move After Class

  1. 1. Enroll clickers
  2. 2. Today: Some administrative stuff Matter is atoms, Brownian motion, Scanning tunneling microscopy <ul><li>If you missed Tuesday’s class </li></ul><ul><ul><li>Do HW #1 on vista.unm.edu !!! </li></ul></ul><ul><li>Next homework will be assigned tomorrow night, </li></ul><ul><li>due Tuesday before lecture (check WebCT) </li></ul>
  3. 3. WebCT Demo
  4. 4. What is Physics? <ul><ul><li>Physics is about the nature of basic things such as motion, forces, energy, matter, heat, sound, light, and the structure of atoms. </li></ul></ul><ul><ul><li>Our Textbook </li></ul></ul><ul><ul><li>Wikipedia </li></ul></ul><ul><ul><li>Physics is the science of matter and its motion , as well as space and time — the science that deals with concepts such as force , energy , mass , and charge . Physics is an experimental science , and it is the objective of physicists to understand how the natural world works. </li></ul></ul>Physics is the natural science which examines basic concepts such as energy , force , and spacetime and all that derives from these, such as mass , charge , matter and its motion . More broadly, it is the general analysis of nature , conducted in order to understand how the world and universe behave. 2008 2009 Students Tuesday Behavior of matter; How bodies interact; how stuff works; the law of motion; understanding chemistry; natural and unnatural force (manmade);
  5. 5. Brainstorming: What’s in this room? (If I don’t hear, shout again!) A Dark matter Quarks Electrons heat B Molecules Atoms Oxygen CO2, H20 Neutrons, protons, steam C People/students Desk, chairs, lights, chalkboard, air, neutraphils, bacteria, thoughts, pheremones, dust, C A’ Dark energy Space-time, heat, B’ Light waves, sounds waves (waves), gravity, motion, interactions C’ God, ideas, Jesus, thoughts, ___ual tension, physics
  6. 6. Brainstorming: What’s in this room? (If I don’t hear, shout again!) A quarks Electrons Photons(waves?) B Oxygen, CO2, carbon Atoms & molecules Protons neutrons C People, Electronics Materials (Furniture,shoes,sheets) Air, sensors A’ Heat, energy, Gravity, space-time B’ Light (radiowaves), sound, color, shadows, pressure, motion, C’ Electricity, smell Emotions Thoughts Mathematics Geometry Architecture physics Fundamental particles Complex materials “ Pure” materials Fundamental abstract things Complex abstract things Complex abstract things ?
  7. 7. Brainstorming: What’s in this room? (If I don’t hear, shout again!) A quarks Electrons Photons(waves?) B Oxygen, CO2, carbon Atoms & molecules Protons neutrons C People, Electronics Materials (Furniture,shoes,sheets) Air, sensors There are many physics concepts here, and there is no way we can cover them in order! A’ Heat, energy, Gravity, space-time B’ Light (radiowaves), sound, color, shadows, pressure, motion, C’ Electricity, smell Emotions Thoughts Mathematics Geometry Architecture physics Fundamental particles Complex materials “ Pure” materials Fundamental abstract things Complex abstract things “ Pure?” abstract things
  8. 8. Powers of 10 video This video explores our universe in powers of 10 for length scales (i.e. 1 meter, 10 meters, 100 meters, 1kilometer, etc.) It’s a bit old and hokey, but still pretty cool. It ends at the length scale we’ll talk more about today: very small (atoms) Feynman apple
  9. 9. Clicker Question <ul><li>If you put a drop of food coloring into a cup of corn sryup, what happens over course of time? </li></ul><ul><li>Drop stays exactly where it is </li></ul><ul><li>Drop slowly spreads out </li></ul>Why?
  10. 10. Brownian motion as evidence for existence of atoms It took over 80 years in 1800-1900’s for scientists to become convinced about atoms
  11. 11. “ pollen grains” jiggle perpetually in room temperature water Fluorescent microspheres (1/1000 th of a millimeter) in water tethered to slide with single DNA molecules Viewed through a microscope… why are they jiggling???
  12. 12. Overhead Brownian Motion Demo In this demo, we are looking at the shadows of small spheres being shaken by a motorized corral Q: What will happen when we add a bigger ball bearing to the medium-sized ones? A: It will move more slowly than the medium-sized ones B: It will move the same as the medium-sized ones C: It will move more quickly than the medium-sized ones Discuss with your neighbors
  13. 13. Brownian motion in surprising places! (Laser demo) In this demo, we will be using laser light (described later in course) and seeing what it looks like when we shine on dry versus wet paint Dry paint: Keep your head very still, then move head slightly back and forth. Q: What is paint made of? Q: What do you think will happen with the wet paint?
  14. 14. A few key points about Brownian motion <ul><li>Atoms are not stationary! </li></ul><ul><li>Book misleads you, though – overall diffusion is VERY slow. </li></ul><ul><li>The smaller things get, the more important is Brownian motion </li></ul><ul><li>Let’s look at something small again Prof. Diane Lidke (UNM Pathology) movie (4) </li></ul>
  15. 15. Clicker Question <ul><li>How is the below image made (similar to the book figure 11.5, iron atoms on cobalt)? </li></ul><ul><li>Computer simulation </li></ul><ul><li>Powerful light microscope (stereo) </li></ul><ul><li>By measuring electron current from a scanning sharp probe </li></ul><ul><li>Scattering electron waves </li></ul>http://www.almaden.ibm.com/vis/stm/corral.html Discuss with your neighbors
  16. 16. Clicker Question <ul><li>How is the below image made (similar to the book figure 11.5, iron atoms on cobalt)? </li></ul><ul><li>Computer simulation </li></ul><ul><li>Powerful light microscope (stereo) </li></ul><ul><li>By measuring electron current from a scanning sharp probe </li></ul><ul><li>Scattering electron waves </li></ul>http://www.almaden.ibm.com/vis/stm/corral.html Brownian motion is indirect evidence of existence of atoms Scanning tunneling microscopy seems even more direct
  17. 17. Scanning Tunneling Microscopy http://www.ieap.uni-kiel.de/surface/ag-berndt/mikro/images/stm-320.jpg http://www.nrc-cnrc.gc.ca/multimedia/picture/images/html/nrc-nint_scan_tunn_mic-lr.jpg
  18. 18. STM can be used to build fun things one atom at a time http://www.almaden.ibm.com/vis/stm/corral.html Iron atoms on copper crystal Do you notice anything else in these images?
  19. 19. Structure of the atom Atom is composed of protons & neutrons in a dense “nucleus” Much less massive electrons “orbit” the nucleus in “shells” or “clouds” User:Yzmo on wikimedia commons
  20. 20. Clicker Question <ul><li>Is an atom mostly solid or mostly empty space? </li></ul><ul><ul><li>a) Solid b) Empty space </li></ul></ul>
  21. 21. Clicker Question <ul><li>Is an atom mostly solid or mostly empty space? </li></ul><ul><ul><li>a) Solid b) Empty space </li></ul></ul>Stipe et al. Science 279 , p.1907 Oxygen molecules on top of Silicon crystal (very cold!) Author of textbook says empty space… Doesn’t seem like empty space to me
  22. 22. Check WebCT this weekend!!! <ul><li>HW due Tuesday </li></ul><ul><li>Reading Tuesday / Thursday </li></ul><ul><li>Quiz due next Thursday </li></ul>
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