1. Please find your NEW seat. Take out your planners!
Happy Almost Break!
Please find your NEW seat.
Take out your planners!

2. Unit 4 Test Results Multiple Choice- 48 pts. (2 per question)
Short Answer- 20 pts.
May retake them separately
Multiple Choice:
A =
B =
C = Retakes for 33 and below
D = 29-33
Period 1: 66.67% Period 6: 68.96%
Period 2: 68.67% Period 8: 69.42%
Period 3: 69.89%
Short Answer:
A = 21-23
B =
C = Retakes for 14 and below
D = 14-16
Period 1: 73.0% Period 6: 59.30%
Period 2: 69.70% Period 8: 65.25%
Period 3: 68.60%

3. Test Corrections/ Extra Credit/ Retakes DUE January 11th!
Extra Credit assignment is posted on my swift site!

4. Learning Targets
HIT ME!

5. Where math and chemistry come together in perfect harmony.
Numbers Unit
Where math and chemistry come together in perfect harmony.

6. Warm-Up: Precision in Your Life!
Come up with five “tools” you use frequently that estimate numerical values for you. (Ex: a clock!)
How precise is each tool?
When does something need to be precise?
When doesn’t it matter?

7. Math the Chemistry Way!
Sig Figs Notes

8. Measurement Basics All measurements have a degree of uncertainty
The less precise the measuring tool, the more uncertain the measurement
In Chemistry calculations, we follow rules to indicate how precise a number is
These rules involve “significant figures”- all certain numbers plus the first estimated one

9. Significant Figures Any digit is significant if it is … 1) A non-zero
24.7 _________ __________
2) A zero between non-zeros
7003 _______ __________
3) A zero at the end of a number and after a decimal (these show degrees of accuracy)
43.00 __________ _____________
4) Part of an exact or counted number
60 minutes = 1 hour 24 students in the class 4 3 4 4 4 4

10. Digits are not significant if they are…
5) To the left of non-zeros (these are place holders)
_____ ______
6) At the end of a number and there is no written decimal (show degree of accuracy)
4100 _________ 300 _________
**Exception: If a decimal is written, the zeros are significant
4100. ________ 2 3 2 1 4

11. Types of Zeros: Leading zeros  Never significant
Captive zeros  Always significant
Trailing zeros  Sometimes significant, depends on decimal

12. Adding and Subtracting with Sig Figs
Example:
Step 1: Determine the “real” answer 
Step 2: Determine the number of Decimal Places in original numbers
13.50  2 decimal places
7.2  1 decimal place
 3 decimal places
Step 3: Round answer to the least number of decimal places
Answer should have 1 decimal place
becomes 44.2

13. Multiplication & Division with Sig Figs
Example: 7.71 x 5.4
Step 1: Determine the “real” answer 
Step 2: Determine the number of Significant Figures in original numbers
7.71  3 significant figures
5.4  2 significant figures
Step 3: Round answer to the least number of significant figures
Answer should have 2 significant figures
becomes 42

14. The Tough Ones…
26.972−
Assume parenthesis! (26.972−3.5) ( )
Calculate top and bottom halves separately and round to appropriate decimal place (addition and subtraction rules)
becomes
Then divide and round to lowest # sigfigs (multiplication and division rules)
= Round to 3.5

15. Another Example (23.1 + 5.61 + 1.008) × 7.6134 × 8.431=?
Calculate addition first and round to tenths
Multiply it with the other two and round to the lowest # sigfigs
(29.7) x x =  1910

16. Homework for next class
Finish Sig Figs Worksheet

17. Significant Figures
Any digit is significant if it is … 1) A non-zero 24.7 _________ 2458 __________ 2) A zero between non-zeros 7003 _______ __________ 3) A zero at the end of a number and after a decimal (these show degrees of accuracy) __________ _____________ 4) Part of an exact or counted number 60 minutes = 1 hour 24 students in the class

18. Digits are not significant if they are…
5) To the left of non-zeros (these are place holders)
_____ ______
6) At the end of a number and there is no written decimal (show degree of accuracy)
4100 _________ 300 _________
**Exception: If a decimal is written, the zeros are significant
4100. ________

19. Adding and Subtracting with Sig Figs
Example:
Step 1: Determine the “real” answer  _________
Step 2: Determine the number of Decimal Places in original numbers
13.50  ___ decimal places
7.2  ____ decimal place
 ____ decimal places
Step 3: Round answer to the least number of decimal places
Answer should have _____ decimal place
_________ becomes ______

20. Multiplication & Division with Sig Figs
Example: 7.71 x 5.4
Step 1: Determine the “real” answer  __________
Step 2: Determine the number of Significant Figures in original numbers
7.71  _____ significant figures
5.4  _____ significant figures
Step 3: Round answer to the least number of significant figures
Answer should have _____ significant figures
_________ becomes ________