1. Do Now – September (prime number between 20 and 28), 2009
Please answer the following questions in
COMPLETE SENTENCES.
Write a sentence describing what a theory is.
Why weren’t cell phones invented when regular phones were?

2. Agenda Do Now/Announcements Unit 2 Test Results and Personal Tracking
Review Theories
Read article and finish Friday’s notes
Evolution of Atomic Theory #1
Work Time (?)
Exit Ticket

3. Unit 2 Test Results – 2nd Period
100% or above
Chris Treadway
90% and above
Raul Baca
Diquan Forcell
Dalvin Hickerson
Ronald Jackson
Omar Martinez
Blake Percle
Alexandria Sierra
Brandon Toney
CLASS AVERAGES
2nd: 85
3rd: 85

4. Unit 2 Test Results – 3rd Period
100% or above
Isaac Wallis
90% and above
Patrick Beckham
Jasmine Castro
Jonathan Cordero
Christina DeArmas
Kaynetra Hunter
Angelle Johnson
De’Shawn Lemieux
Jontrel Mackey
Laronda Severance
Cachi Tran
Steven Webb
CLASS AVERAGES
2nd: 85
3rd: 85

5. Unit 2 Test Results – 4th Period
95% or above
Other As and Bs
Carolyn Dhanraj
Robin Foucha
Briana Petes
Carlos Turner
CLASS AVERAGES
2nd: 78
3rd: 76
4th: 71

6. Objectives SWBAT describe and discuss how theories change over time.
SWBAT describe the evolution of the atomic theory from 420 B.C. to 1898.
SWBAT defend a conclusion using research as evidence.

7. Review
A theory is an explanation that has been supported by many, many experiments
Supported over time
Subject to new experimental data and can be modified
Used to make predictions that are true

8. How is a THEORY different from a HYPOTHESIS?
A theory is an explanation that has been supported by many, many experiments
Experiments have already been conducted to support a theory
A hypothesis is a tentative explanation for observations that have already been made
Experiments must be conducted to test hypothesis

9. CONCLUSIONS
A conclusion is a judgment based on information obtained in an experiment
Scientists apply DATA to HYPOTHESIS to form CONCLUSION

10. Remember!
A hypothesis is a tentative explanation for observations that have already been made
A conclusion is a judgment based on information obtained in an experiment
A theory is an explanation that has been supported by many, many experiments (related to a scientific law)

11. So what is a SCIENTIFIC LAW?
A scientific law is a description of nature supported by many experiments
It is a simple description
A theory describes how the law works
Theories and laws are similar

12. What is an ATOM?
An atom is the smallest part of an element that retains (keeps) the properties of the element
Remember! Particles hold the identity of matter!

13. What is an ELEMENT?
An element is a pure substance that cannot be broken down into simpler substances by physical or chemical means

14. So How’d They Do It?
How do you think scientists learned about the particles of a substance when they couldn’t even see them?
In other words, how did they know that all matter was made of tiny particles?

15. Unit 3 Chemistry Secrets: Atoms and the Periodic Table
What should we understand?
History and science are intertwined. We can look back on history and see just how the atom and periodic table were developed. The
atom is so central to our understanding of
chemistry because it is these particles that
determine what we can observe about all matter. Everything is composed of atoms. Some of our most pressing international debates today revolve around the structure and properties of the atom. We have to be informed of ALL models of the atom.

16. Essential Questions
Who made the most important contribution to the development of atomic theory?
What makes one atom different from another? How are they similar?
Why is it so important to understand how the periodic table is organized?
What secrets can we uncover about the elements using the periodic table?

17. How in the World Did They Figure All this Out!?!

18. Big Players in Atomic Theory
Democritus ( B.C.)
Aristotle ( B.C.)
John Dalton (1808)
J.J. Thomson (1898)
R.A. Millikan (1909)
Ernest Rutherford (1909)
Niels Bohr (1913)
Chadwick (1932)

19. Numero Uno! - Democritus (460-370 B.C.)
Experiment: Observations and Inferences (no REAL experiment…just IDEAS)
Where: Greece
When: 420 B.C.
First theory of the atom
The “birth” of the atom

20. Democritus - Conclusions
Matter is composed of tiny particles
Named them atomos (Greek)
Different kinds of particles have different sizes and shapes
Particles move through empty space
Page 88

21. Number 2 - Aristotle (384-322 B.C.)
Aristotle gave us this quote…
“We are what we repeatedly do. Excellence, therefore, is not an act but a habit.”
Among other things…
He challenged the ideas of Democritus
He did not think the “nothingness” of empty space could exist
Page 88-89

22. Coming in Third… John Dalton (1766-1844)
Experiment: Careful chemical measurements
Where: England
When: 1803
Page 90

23. Four Postulates All matter is made of tiny particles called atoms.
All atoms of a given element are identical, but they differ from those of any other element.

24. Four Postulates
Compounds are formed by a combination of 2 or more types of atoms.
Chemical reactions occur when atoms are rearranged.

25. John Dalton’s Conclusions
Dalton thought that atoms were hard, round, solid balls
(like marbles)

26. Cuatro! J. J. Thomson (1856-1940) Experiment: Cathode ray tube
When: 1898
Where: England

27. + E E E E
CONCLUSIONS
He said the atom was a ball of positive charge with electrons evenly spaced in the atom
Atoms can be divided into smaller SUBATOMIC particles!

28. What are the similarities and differences between each contribution?
Compare and Contrast
What are the similarities and differences between each contribution?
How did each theorist add to or reject the discoveries or ideas developed before him?

29. RAFT - Independent Work Time
R = Role
Pretend to be either Dalton or Thomson.
A = Audience
You are writing to inform everyone of your discoveries!
F = Format
Letter, Newspaper column, or Rap
T = Topic
Details of your discovery and how you know it is true - YOU HAVE “WORKED” HARD…DEFEND YOUR RESEARCH!
You may use a chemistry book to help.

30. Exit Ticket
Can people think that theories are correct even when they are not? How does this happen? How is it that theories change?
What was Dalton’s biggest contribution to atomic theory?
If you achieved the class average on your test, what did you do to get that grade and how will you continue in the future? If you did not get the class average on your test what will you do differently next time to make sure that you do better?

31. Cinco! R. A. Millikan
Experiment: Millikan Oil Drop Experiment
When: 1909
Where: U.S.A!!!!

32. Conclusion:
Electrons have negative charges!!!

33. Number Six! Ernest Rutherford
Experiment: Gold Foil Experiment
When: 1910
Where: Montreal

34. Ernest Rutherford Discovered and named the nucleus
Conclusions:
Discovered and named the nucleus
Protons and mass concentrated at center of atom
Performed the alpha-scattering gold foil experiment

36. More History Ernie’s (Rutherford) Big Adventure Thin Sheet of Gold
Atoms

37. - + - +

38. Rutherford’s Conclusion
Atoms are made of mostly EMPTY SPACE!
Actually, the ratio of the size of the nucleus to the diameter of the orbits of electrons can be compared with placing a marble in the middle of a football stadium!

39. Empty Space Continued
“Neutrons and protons occupy the atom's nucleus. The nucleus of an atom is tiny -- only one-millionth of a billionth of the full volume of the atom -- but fantastically dense, since it contains virtually all the atom's mass. As Cropper has put it, if an atom were expanded to the size of a cathedral, the nucleus would be only about the size of a fly -- but a fly many times heavier than the cathedral.” -A Short History of Nearly Everything by Bill Bryson

40. Assignment: RAFT Option 1: Rap Role: An atomic Theorist
Audience: Writing to another atomic theorist
Form: an appropriate rap
Topic: Why your theory and model is better than theirs
+3 points for presenting on Monday

41. Assignment: RAFT Option 2: Polite, Formal Letter
Role: An atomic Theorist
Audience: Writing to another atomic theorist
Form: a formal letter
Topic: Politely stating why your theory and model proves theirs wrong
+3 points for presenting on Monday

42. Assignment: RAFT Things to Include
Personal information about both theorists - where they’re from, physical appearance, etc.
All necessary facts about both theories or models
How the theory is better than the one that came before it

43. I’d like you to meet my friend, and your newest friend in Chemistry… The Periodic Table of Elements

44. On the periodic table there are letters that symbolize the elements.
An element is a substance that is made up of the same type of atom.
Example: Aluminum. An aluminum can is made up of TONS of atoms. They are all aluminum particles.

45. Periodic Bingo
Place a dot on the element as it is called. See if you can get BINGO!!!!

46. Atomic Number = Defines the atom
Top Number OR always the smaller number
Equals the Number of protons in the atom

47. Which element has the atomic number???6 13 35

48. Which element has the atomic number???10 82 47

49. Atomic Mass = mass of the nucleus
Bottom Number  OR always the bigger number
Equals the number of protons and neutrons

50. Which element has an atomic mass of…12 27 11

51. Which element has an atomic mass of…56 31
238