1. Lab Safety List 3 unsafe lab activities you see in the picture.
List 3 lab activities that you see in the picture.
What should Bob do after the accident?
What should Sue have done to avoid the accident?
Look at Duke’s and Luke’s lab procedure. Who is doing it correctly?

2. Lab Safety What are three things that should not be in the lab?
Compare Joe’s and Carl’s lab techniques. Who is doing it correctly?
What will happen to Ray and Tim if the teacher catches them?
List three items that are in the lab for student safety?
What is Betty doing wrong?

3. Significant Figures in Calculations
Unit 1
Significant Figures in Calculations

4. Significant Figures in Measurement
The numbers reported in a measurement are limited by the measuring tool
Significant figures in a measurement include the known digits plus one estimated digit
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5. Timberlake lecture plus
Definitions
Significant Figures: each of the digits of a number that are used to express the necessary degree of accuracy.
Accuracy: the state of being correct or precise. (your arrows were on the bulls eye)
Precise: being exact (you were given the exact amount of change)
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6. Counting Significant Figures
Number of Significant Figures
38.15 cm 4
5.6 ft 2
65.6 lb ___
m ___
Complete: All non-zero digits in a measured number are (significant or not significant).
Timberlake lecture plus

7. Timberlake lecture plus
Leading Zeros
Number of Significant Figures
0.008 mm 1
oz 3
lb ____
mL ____
Complete: Leading zeros in decimal numbers are (significant or not significant).
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8. Do Now…
Tell how many significant figures are in the following numbers.
___ ____
___ ____
___ ____
___
___

9. Timberlake lecture plus
Sandwiched Zeros
Number of Significant Figures
50.8 mm 3
2001 min 4
0.702 lb ____
m ____
Complete: Zeros between nonzero numbers are (significant or not significant).
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10. Timberlake lecture plus
Trailing Zeros
Number of Significant Figures 25,000 in
200 yr 1
48,600 gal 3
25,005,000 g ____
Complete: Trailing zeros in numbers without decimals are (significant or not significant) if they are serving as place holders.
Timberlake lecture plus

11. Timberlake lecture plus
Learning Check
A. Which answers contain 3 significant figures?
1) ) ) 4760
B. All the zeros are significant in
1) ) ) x 103
C. 534,675 rounded to 3 significant figures is
1) ) 535, ) 5.35 x 105
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12. Timberlake lecture plus
Solution
A. Which answers contain 3 significant figures?
2) ) 4760
B. All the zeros are significant in
2) ) x 103
C. 534,675 rounded to 3 significant figures is
2) 535, ) 5.35 x 105
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13. Timberlake lecture plus
Learning Check
In which set(s) do both numbers contain the same number of significant figures?
1) and 22.00
2) and 40
3) and 150,000
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14. Timberlake lecture plus
Solution
In which set(s) do both numbers contain the same number of significant figures?
3) and 150,000
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15. Do Now…
List the following numbers in scientific notation or if they are in scientific notation convert to regular number.
2.3 x
x 105
2.3 x x 10-12
9.0 x 1029

16. Timberlake lecture plus
Learning Check SF3
State the number of significant figures in each of the following:
A m
B L
C g
D m
E. 2,080,000 bees
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17. Timberlake lecture plus
Solution
A m 2
B L 4
C g 1
D m 3
E. 2,080,000 bees 3
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18. Significant Numbers in Calculations
A calculated answer cannot be more precise than the measuring tool.
A calculated answer must match the least precise measurement.
Significant figures are needed for final answers from
1) adding or subtracting
2) multiplying or dividing
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19. Do Now…
Calculate the following numbers and report to the correct number of significant figures.
2.3 x =
5640 / = =
2.3 x x 3.2 x =
9.0 x x 3.0 x =

20. Adding and Subtracting
The answer has the same number of decimal places as the measurement with the fewest decimal places.
one decimal place
two decimal places
26.54
answer one decimal place
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21. Do Now…
Estimate the following numbers to the correct 1 significant figure.
miles =
grams =
0.160 liters =
Estimate the following numbers to the correct 2 significant figure.
2305 cm =
km =

22. Timberlake lecture plus
Learning Check
In each calculation, round the answer to the correct number of significant figures.
A =
1) ) ) 257
B =
1) ) ) 40.7
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23. Timberlake lecture plus
Solution
A =
2) 256.8
B =
3) 40.7
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24. Multiplying and Dividing
Round (or add zeros) to the calculated answer until you have the same number of significant figures as the measurement with the fewest significant figures.
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25. Timberlake lecture plus
Learning Check
A X 4.2 =
1) ) )
B ÷ =
1) ) ) 60
C X =
X 0.060
1) ) )
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26. Timberlake lecture plus
Solution
A X = 2) 9.2
B ÷ = 3) 60
C X = 2) X 0.060
Continuous calculator operation = x  
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27. Timberlake lecture plus
Reading
Physics reading:
Chemsitry reading:
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