Atomic Theory and Model Webquest
Section 1: Atomic Thoughts – Democritus
(http://www.universetoday.com/60058/democritus-atom/)
1. When did Democritus live?
2. What makes up everything accord to Democritus?
Section 2: Advanced Atomic Thoughts – John Dalton
 Read http://chemed.chem.purdue.edu/genchem/history/dalton.html
 Read http://www.iun.edu/~cpanhd/C101webnotes/composition/dalton.html
 Read http://www.chemicalformula.org/chemistry-help/models-of-the-atom (look for
John Dalton)
3. What year was John Dalton’s Atomic Theory released? Summarize (in your own words)
the FIVE parts to Dalton’s Atomic Theory.
4. What are two problems with Dalton’s Atomic Theory today?
5. What was John Dalton’s model of the atom called?
6. What year did he propose his atomic model? About many years is this from
Democritus?
Section 3: Experimental Beginnings of the Atom – J.J. Thomson
 Read http://www.chemteam.info/AtomicStructure/Disc-of-Electron-Images.html
 Read http://www.chemicalformula.org/chemistry-help/models-of-the-atom (look for
Thomson)
7. “Atoms are small, indivisible particles. There is nothing smaller than an atom.” Why
would Thomson disagree with this statement?
8. What subatomic particle did Thomson first discover?
9. What is the name of Thomson’s model of the atom? What year did he propose it?
10.What is the name of the main piece of equipment used by Thomson? Do some research
on this equipment. What is it commonly found in today?
Section 4: Advanced Experimenting – Ernest Rutherford
(http://myweb.usf.edu/~mhight/goldfoil.html)
11.What was the name of Rutherford’s most famous experiment?
12.Describe and/or illustrate what Rutherford’s experiment looked like.
13.What did Rutherford conclude was in the middle of the atom?
14.J.J. Thomson said the atom is filled with “positive sea” with small, negative particles
called electrons. Would Rutherford agree or disagree with this statement? Why?
Section 5: Bohring Atoms – Niels Bohr (
http://www.pbs.org/wgbh/aso/databank/entries/bpbohr.html)
15.Opposites attract. Should spinning negative electrons be attracted to the nucleus? YES
– but they never stop spinning around! How did Bohr explain this? (3rd Paragraph)
16.What happens to an electron’s location when it absorbs energy? What happens when it
radiates energy?
Section 6: Quantum Mechanical Model/Electron Cloud Model
Read http://www.sparknotes.com/testprep/books/sat2/chemistry/chapter4section4.rhtml
17.Describe the main difference regarding electron location in the Bohr model vs. the
current Quantum Model.
18.Describe Werner Heisenberg’s Uncertainty Principle. How does this help explain current
thoughts about electron location in the Quantum Model?
Section 7: Misc. Factoids (Chadwick)
19.James Chadwick is credited with discovering which subatomic particle? (Search Yourself)
20.Robert Millikan discovered something pretty important about the electron.
 View Video at
http://cleanvideosearch.com/media/action/yt/watch?videoId=XMfYHag7Liw
 What was his experiment called?
 What did he discover about the electron?
Timeline – use guide at http://www.chemicalformula.org/chemistry-help/models-of-the-atom
Create a timeline with the following models: Dalton, Thomson, Rutherford, Bohr, and
Quantum. Illustrate the models pictorially. You may draw or use the computer. Include:




Names of discoverer and model name
Picture of the Atom as the discover saw it
The year of discovery/release
The significant difference between one model and
the next
Turn in Finished Timeline!
Each person in the group
should turn in their own
unique version.