Discovering the Atom

Discovering the Atom Instructions: Go to each website and use the information and animations to answer the questions. This is an exploration....explore. The links should work.....if they do not, try cutting and pasting the address into your browser. If you come across other interesting sources, please share. The questions should be answered in full detail, on a separate sheet of paper or in the MOODLE if your teacher has assigned it there. Your textbook also contains useful information on the history of the atom. For questions 1 and 2: http://www.chemteam.info/AtomicStructure/Greeks.html http://instruct.westvalley.edu/lafave/Aristotle_de_anima.html 1a. According to Democritus, what is the composition of matter? 1b. What is the root of our word "atom" and how is this root misleading? 1c. Aristotle described matter as being composed of hyle, what does that mean about how matter looks or behaves. For questions 3 and 4: http://higheredbcs.wiley.com/legacy/college/olmsted/0471478113/dialogue/dialogues/info_dalto n.swf http://antoine.frostburg.edu/chem/senese/101/atoms/dalton.shtml

3. What are the five main ideas of Dalton's theory? What idea compromised the acceptance of his work? 4. Which of the basic ideas of Dalton's Atomic Theory is an extension of what the Greeks believed about atoms? Watch this You tube video which explains what scientists knew at the time about electricity and magnetism rod and balls Write a summary and conclusion from the simulation you watched.

For questions 5 and 6: http://www.crtsite.com/page7.html http://science.howstuffworks.com/dictionary/famous-scientists/chemists/crookes-info.htm http://www.wwnorton.com/college/chemistry/gilbert2/tutorials/interface.asp? chapter=chapter_02&folder=cathode_ray http://library.thinkquest.org/28582/history/crayexp.htm 5. How did William Crookes determine the nature of the beam in cathode ray tube?

6. What did he conclude from his experiment? For questions 7, 8 and 9: http://www-outreach.phy.cam.ac.uk/camphy/electron/electron_index.htm http://www.aip.org/history/electron/jj1897.htm http://www.aip.org/history/electron/jjelectr.htm http://www-outreach.phy.cam.ac.uk/camphy/nucleus/nucleus1_1.htm

Watch the you tube video and write a summary: cathode ray explanation go back to the 4th site when you are answering question 14 7. How did Thomson use the cathode ray tube in his research?

8. What did Thomson conclude based on his research?

9. How did Thomson’s findings revise Dalton’s Atomic Theory? For questions 10-13 http://g.web.umkc.edu/gounevt/Animations/Animations211/MillikanOilDropExp.swf http://www.wwnorton.com/college/chemistry/gilbert2/tutorials/interface.asp? chapter=chapter_02&folder=millikan http://www.montereymotiongraphics.com/example1.swf http://www.webassign.net/resources/serpse8/activeFigures/25.22.swf Millikan's Oil Drop Experiment: Visit the four sites above and then go back to the simulation at the last link (webassign.net) and complete 10-13. 10. Press the bulb of the atomizer and observe. Describe what happens to the oil drops. 11. Now turn on the circuit, by pressing the button on the bottom right so that it goes from reading OFF, to reading ON. Spray the atomizer again. Describe the behavior of the drops. 12. Now play with the voltage by changing the potential difference. Spray the atomizer and observe. Move the voltage up and down and observe the drops. Record the voltage that makes some of the drops stay suspended in the middle of the apparatus. 13. Based on the interaction between the oil drops and the electric field, what did Millikan conclude? For questions 14: http://www.chemteam.info/AtomicStructure/Disc-of-Electron-Intro.html http://www.iun.edu/~cpanhd/C101webnotes/modern-atomic-theory/rutherford-model.html

14. Describe and sketch Thomson’s model of the atom. What is wrong with the picture presented on the www.iun.edu page? Go back to the 4th site above number 7 and see the diagram on the left…either copy and paste it or draw it. For questions 15-17: http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/ruther14.swf http://www.wwnorton.com/college/chemistry/gilbert2/tutorials/interface.asp? chapter=chapter_02&folder=rutherford_experiment http://www.iun.edu/~cpanhd/C101webnotes/modern-atomic-theory/rutherford-model.html http://micro.magnet.fsu.edu/electromag/java/rutherford/ information is good, java applet won’t work at school. http://chemmovies.unl.edu/ChemAnime/RUTHERFD/RUTHERFD.html http://phet.colorado.edu/en/simulation/rutherford-scattering http://en.wikipedia.org/wiki/Geiger%E2%80%93Marsden_experiment

15. What materials did Rutherford (and his students Geiger and Marsden) use for the gold foil experiment? 16. How did Rutherford’s experiment disprove Thomson’s model of the atom?

17. What new model did Rutherford propose? Sketch it.

Watch this you tube video about the Rutherford experiment and write what three things happen to the alpha particles. rutherford experiment For questions 18: http://www-outreach.phy.cam.ac.uk/camphy/neutron/neutron1_1.htm http://www.chemcases.com/2003version/nuclear/nc-01.htm http://www.nature.com/physics/looking-back/chadwick/index.html

18. Which subatomic particle did James Chadwick discover? Compare its mass to that of a proton.

For questions 19-22: http://www.physics.isu.edu/radinf/cuire.htm http://science.hq.nasa.gov/kids/imagers/ems/xrays.html

19. Who was credited with the discovery of X-rays?

20. What important discovery did Becquerel make upon examining a piece of pitchblende wrapped up in paper? (Pitchblende is a source of uranium)

21. What two elements did the Curies discover?

22. Becquerel was credited with discovering radioactivity, the spontaneous emission of radiation by a material. He also noticed that both X-rays and the radiation emitted by uranium had strong effects on photographic film, yet they are not the same. What important difference between radiation emitted by uranium and X-rays led him to this conclusion? Modern Model of the atom: All about the Bohr Model: bohr model simulation of bohr model Desribe the bohr model, where are electrons, draw a picture, what did it have to do with energy of electrons

And Now the most recent model: Erwin Schrodinger’s work gave us the most modern model of the atom. cloud model Schrodinger's model bohr and schrodinger model simulation

This site has a nice summary of it all with some animations and videos for you to look at take notes and LEARN! Stop reading after the Paragraph with Schrodinger’s name. summary from Democritus to Schrodinger