1. Unit 2: Atoms and their electrons
Converting between two sets of units never changes the number of significant figures in a measurement. Remember, data are only as good as the original measurement, and no later manipulations can clean them up.

2. Claim, Evidence, and Reasoning
What is a claim? Define in your own words…
Claim: A statement of your understanding that answers the original question.
A one-sentence answer to the question you investigated
Must be specific!
It should not start with yes or no.

3. Claim, Evidence, and Reasoning
What is considered evidence? Define in your own words...
Evidence: Scientific data used to support the claim.
Evidence must be:
Sufficient—Use enough evidence to support the claim.
Qualitative: Can be observations (see, smell, hear, feel).
Quantitative: Can be numbers or data from measurements.

4. Claim, Evidence, and Reasoning
What is your reasoning? Or, what is your explanation for why your evidence supports your claim?
Reasoning: Ties together the claim and the evidence.
Shows how or why the data count as evidence to support the claim.
Provides the justification (or reason) for why this evidence is important to this claim.

5. CER Examples from Bunsen Burner Lab…

6. Claim, Evidence, and Reasoning Exercise
Take out a piece of paper, write your name, period, and date on the top.
Write ‘Claim’ and skip 4 lines
Write Evidence and number 1, 2, 3, 4, 5
Write Reasoning.

7. Claim, Evidence, and Reasoning Exercise
We will watch the video. After you will answer the following:
What is the little girl’s claim?
What data or evidence does she give us?
How do her observations (or evidence) support her claim?
tube.com/watch? time_continue=1 &v=WQTsue0lKB k

8. Claim, Evidence, and Reasoning Exercise
Fill in the Claim, Evidence, and Reasoning sections on your paper
Share with your table group.
Come to an agreement and be ready to share! 
h?time_continue=1&v=WQTsue 0lKBk

9. Introduction to Atoms
Send up a person from your table to collect supplies (paper, glue)
Label the paper with your names and period and ‘Unit 2 Concept Map’
Share with your table group what you have written
Remove any duplicates – You must have at least 6 different things on your concept map.

10. Introduction to Atoms
Group related things together and make a label for the group
Now assemble your squares/groups on your paper so they are in an explicable pattern or grouping
Once your group agrees on the pattern or grouping, glue down your squares and draw arrows connecting and explaining the connections you made.

11. Introduction to Atoms Now watch this video

12. Introduction to Atoms
Now add 1 new square per person in your table group to your concept map!
You should have at least 10 squares on your concept map.
Check and see if you need to revise anything (maybe put it under a different label/grouping?)

13. Introduction to Atoms PHeT Activity Go to this website:
Complete the ‘Exploring the Structure of the Atom’, front page only.

14. Introduction to Atoms
Electron distribution activity

15. Get out Electron data tables and graph paper

16. Jigsaw
Get notes and each person (starting with Document #1, then #2, #3, and #4) share with your table group what you learned from your article (1.5 Minutes each)

17. Jigsaw Get a white board and marker (send one person from your table)
Each person draw your representation of the atom for each document and list major contribution to theory of atomic structure (we will share these with the class) (3 minutes)
Share out to class

18. The Nuclear Atom
Turn to page 2 and complete the questions while watching the video.

19. Isotopes & Atomic Mass

20. completely new element isotopes of the same element
Atoms
When you change the number of electrons, you get an
When you change the number of neutrons, you get
When you change the number of protons, you get an
ion of the same element
completely new element
isotopes of the same element U
Mass Number →
Can change!
238
Symbols contain the mass number and the atomic number.
Atomic Number →
NEVER Changes 92

21. Isotopes
Definition: atoms with the same number of protons but different numbers of neutrons.
In nature, most elements are found as a mixture of isotopes.
What happens to the mass of the different isotopes?

22. Naming & Writing Isotopes
There are two ways we can write isotopes. We can write the mass as an exponent after the number.
Isotopes of Carbon include:
14 C and 12c
We can also put the mass number after the name of the element:
carbon-12
carbon-14

23. Mass Number vs. Atomic Mass
Mass number: number of protons and neutrons
Atomic mass: the weighted average mass of the isotopes of that element.
Atomic mass unit (amu): one- twelth (1/12) the mass of carbon-12

24. Calculating Atomic Mass
Convert the abundance percentages into decimals (divide by 100)
Multiply the abundance (in decimal form) by the mass of the isotope for each isotope
Add the answers from step 2 together.
Example: A sample of cesium is 75% Cesium-133, 20% Cesium-132 and 5% Cesium What is its average atomic mass?

25. A sample of cesium is 75% 133Cs, 20% 132Cs and 5% 134Cs
A sample of cesium is 75% 133Cs, 20% 132Cs and 5% 134Cs. What is its average atomic mass?
What are the three isotopes in this problem?
cesium 133, 132, and 134
1. Convert percents to decimals (divide by 100)
75% = 20% = 5% =
2. Multiply the percent (in decimal form) by the mass
(0.75) x (133) =
(0.20) x (132) =
(0.05) x (134) =
Average Atomic Mass = amu
3. Add the masses together to get the average atomic mass.
0.75
0.20
0.05

26. Cootie Catcher! Assemble and color your cootie catcher (3.38 minutes!)
You can use colored pencils or markers available up front!

27. Cootie Catcher! Instructions / Procedure:
You and your neighbor will work together.
Person #1 picks a word: Element, Compound, Mixture, or Matter
Person #2 holding the catcher spells out the word, moving the flaps side to side with each letter.
Person #1 chooses one of the inside numbers.
Person #2 moves the flaps however many times of the number chosen.
Person #1 chooses another number.
Person #2 reads the definition for Person #1 to answer