DALTON
HISTORY OF ATOMIC
THEORY
WEBQUEST

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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://www.thebigview.com/greeks/democritus.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?

2. The Greeks believed that fire was a state of matter. How did atomists describe fire?

For questions 3 and 4:
http://higheredbcs.wiley.com/legacy/college/olmsted/0471478113/dialogue/dialogues/info_dalton.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?

For questions 5 and 6:
http://micro.magnet.fsu.edu/electromag/java/crookestube/
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

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?

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/

15. Go to the micro.magnet.fsu site. What do you observe when the slit width is adjusted to 4.0 nm?

16. How did Rutherford’s experiment disprove Thomson’s model of the atom?

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

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?

 

Overview/Review

http://www.iq.poquoson.org/hsscience/chemistry/buildingblocksofmatter/hsbuildingblocksmatter06tlm.htm
http://library.thinkquest.org/C006669/data/Chem/atomic/development.html
http://www.iq.poquoson.org/hsscience/chemistry/buildingblocksofmatter/hsbuildingblocksmatterCloze06tlm.htm

 

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