Chemistry
Atomic Theory
Jigsaw Project
Overview
While working in teams of 2 to 3 and using shared documents, you will answer the following questions about
the development of the modern atomic theory from the time of Democritus to Schrodinger's model of the atom.
Guidelines
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You may use the information provided by the Atomic Timeline or any other electronic and print sources
(your textbook is an excellent resource).
You will be allowed this week and the use of the laptop computers (assuming that you have turned in
your Internet permission form) to complete the work. You may work on the assignment outside of class,
but you are expected to work at least the entire first class period on the project.
You will only be allowed this week (after our planned lessons). Responses are due at the end of class
on Tuesday (9/23) or Wednesday (9/24) of next week.
You will work in teams of two assigned by the teacher.
Each student will turn in their own answers to each of the questions written in their own words in
paragraph form and using correct grammar and spelling. Please feel free to be creative. Include diagrams
or any other enhancement that will make your project more valuable to you. Just be sure to give credit
where credit is due!
How your team works is up to you. You may research each question together or divide up the work and
then share and "teach" each other about the question and its answer. Remember that what you turn in
must be in your own words. You will give your teammates part of their grade, make sure you are
working or your grade will suffer.
You will be tested over this material! Do not just complete the assignment to get it done. Be sure to
know and understand the answers.
I am here to answer in depth questions; you can find the basics on your own. We will go over the most
important highlights in lecture.
Honors Only- As a group, you will pick one of the main contributors to make a poster for. You need to
include all relevant information about his life (birth, death, where he lived… contributions to atomic
theory). I have poster board for you to use.
Honors only- All references will be correctly cited for each question using MLA format. Use
knightcite.com or another online citation site if needed; use citation numbers to show me where you got
your information.
Honors only- The assignment will be created using a word processor and submitted electronically
through Edmodo or email me casteelj@rcschools.net. Edmodo Group code: ________________
Questions to include in Report discussion
Early Greek Philosophers
1. Summarize the five main points of the Greek atomists.
2. Aristotle did not agree with the ideas concerning atoms that were put forth by Democritus. Describe the
differences between Aristotle's and Democritus’ views.
3. Why was the atomic theory discarded until the early 1800's?
John Dalton (1766-1844)
John Dalton was an English chemist. His ideas form the first atomic theory of matter.
Dalton’s Atomic Theory states
1. All elements are composed (made up) of atoms. It is impossible to divide or destroy an atom.
2. All atoms of the same elements are alike. (One atom of oxygen is like
another atom of oxygen.)
3. Atoms of different elements are different. (An atom of oxygen is different
from an atom of hydrogen.)
4. Atoms of different elements combine to form a compound. These atoms
have to be in definite whole number ratios.
 For example, water is a compound made up of 2 atoms of hydrogen and 1 atom of
oxygen (a ratio of 2:1). Three atoms of hydrogen and 2 atoms of oxygen cannot combine
to make water.
5. In chemical reactions, atoms are combined, separated, or rearranged.
a)
b)
c)
d)
e)
What is the name of his theory?
What are elements made of?
An atom of hydrogen and an atom of carbon are ______________________.
Compounds are made up of___________________...
The ratio of atoms in HCl is
i. 1:3
ii. 2:1
iii. 1:1
J.J. Thompson (Late 1800s)
J.J. Thompson was an English scientist. He discovered the electron when he was
experimenting with gas discharge tubes. He noticed a movement in a tube. He called the
movement cathode rays. The rays moved from the negative end of the tube to the positive
end. He realized that the rays were rays were made of negatively charged particles –
electrons.
1. What subatomic particle did J.J. Thompson discover?
2. What is the charge of an electron?
3. What are cathode rays made of?
4. Why do electrons move from the negative end of the tube to the positive end?
5. What was Thompson working with when he discovered the cathode rays?
6. Describe Thomson’s model of the atom.
7. Describe how a cathode ray tube works.
Lord Ernest Rutherford (1871-1937)
Ernest Rutherford conducted a famous experiment called the gold foil experiment. He
took a thin sheet of gold foil. He used special equipment to shoot alpha particles
(positively charged particles) at the gold foil. Most particles passed straight through the
foil like the foil was not there. Some particles went straight back or were deflected (went
in another direction) as if they had hit something. The experiment shows:
• atoms are made of a small positive nucleus; positive nucleus repels (pushes away)
positive alpha particles;
• atoms are mostly empty space.
1. What is the charge of an alpha particle?
2. Why is Rutherford’s experiment called the gold foil experiment?
3. How did he know that atom was mostly empty space?
4. What happened to the alpha particles as they hit the gold foil?
5. How did he know that the nucleus was positively charged?
6. Describe Rutherford's gold foil experiment and how the results changed the model of the atom.
Niels Bohr (Early 1900s)
Niels Bohr was a Danish physicist. He proposed a model of the atom that is similar to the model of the solar
system. The electrons go around the nucleus like planets orbit around the sun. All electrons have their energy
levels – a certain distance from the nucleus. Each energy level can hold a certain number of electrons.
Level 1 can hold 2 electrons, Level 2 – 8 electrons, Level 3 – 18 electrons, and Level 4 – 32 electrons.
The energy of electrons goes up from Level 1 to other levels. When electrons release (lose) energy they
go down a level. When electrons absorb (gain) energy, they go to a higher level.
1. Why could Bohr’s model be called a planetary model of the atom?
2. How do electrons in the same atom differ?
3. How many electrons can the fourth energy level hold?
4. Would an electron have to absorb or release energy to jump from the second energy level to the third
energy level?
5. Describe Bohr's model of the atom.
6. List two problems with Bohr's model.
Quantum Mechanical Theory
1. What are quantum mechanics?
2. Who were Heisenberg and Schrodinger? What were their contributions?
3. What was Debroglie's contribution to the theory of quantum mechanics?
4. What are the 4 quantum numbers? What does each represent?
Evaluation- each response will be scored according to the rubric below.
1
There are major errors in the
response. The answer is unclear
and/or provides little detail.
The response is not in the
student’s own words OR major
errors in grammar and spelling
make the response difficult to
understand. The references
used are not cited.
2
There are minor errors in the
response. It is somewhat
unclear and needs more detail.
An attempt is made to put the
response in the student’s own
words OR Errors in grammar
and spellings are distractive.
The references used are cited,
but not using MLA format.
3
4
Question is answered
accurately. There is adequate
detail to make the response
clear and understandable. The
response is in the student's own
words and minor errors in
grammars and spelling are not
distractive. References are all
properly cited.
Question is answered
accurately and clearly. The
response is extremely detailed
and shows a level of
sophistication in both content
and writing style above grade
level. No errors in grammar or
spelling. References are
properly cited and demonstrate
detailed research.