2. 106,000 aluminum cans, the number used in the US every 30 seconds.

3. How many cans are used in a year?

4. Why would we use scientific notation?

5. REALLY, REALLY SMALL NUMBERS.
SCIENTIFIC NOTATION
A QUICK WAY TO WRITE
REALLY, REALLY BIG OR
REALLY, REALLY SMALL NUMBERS.

6. Rules for Scientific Notation
To be in proper scientific notation the number must be written with
* a number between 1 and 10
* and multiplied by a power of
ten
23 X 105 is not in proper scientific notation. Why?

7. 0.0000187 370,000,000 78.8 0.02164 Change to standard form.
1.87 x 10–5 =
3.7 x 108 =
7.88 x 101 =
2.164 x 10–2 =
370,000,000
78.8

8. Change to scientific notation.
12,340 =
0.369 =
0.008 =
1,000. =
1.234 x 104
3.69 x 10–1
8 x 10–3
1.000 x 103

9. SI System The International System of Units
Derived Units Commonly Used in Chemistry
ONLY 3 countries still use the English system of measurement. (England is not one of them!)
Myanmar (Burma), Liberia, and United States of America
Map of the world where red represents countries which do not use the metric system

10. The International System of Units
Quantity Name Symbol
Length meter m
Mass kilogram kg
Time second s
Amount of substance mole mol
Temperature Kelvin K
Electric current amperes amps
Luminous intensity candela cd
Internet Access to the National Institute of Standards and Technology
“To be or not to be”: the English or the Metric system
The English system of measurement used today in the United States originated in the decrees of English monarchs. The French Revolution produced the overthrow of the French monarchy and in 1799 it also led to the creation of the set of weights and measures we call the metric system. The metric system was legalized for use in the United States in 1866 along with the traditional English system. Today the only countries in the world that do not use the metric system are the United States of America, Liberia and Myanamar.
United States government policy toward the Metric System
This part is to access the following URLs for the National Institute of Standards and Technology, NIST, and review the evolution of the relationship between the United States and the Metric System. You can answer the first question after reviewing this NIST page.
What was the year when the United States signed the “Treaty of the Meter”?
Access this FDA page to answer the following question.
What does the term “Both timeless and toothless” have to do with the Metric Conversions Act of 1975? In your opinion does this influence the pace of metrification in the United States?
Name ____________________ Hr ____
Another part of your assignment is to write a brief argument on the back of this page for adopting the metric system and replacing the English system. Lastly you are to write an argument for continuing the current pattern of using two systems.
Argument for adopting the Metric system and dropping the English system.
Argument for retaining both the English system and the Metric system
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 16

11. NEED TO KNOW Prefixes in the SI System
Power of 10 for
Prefix Symbol Meaning Scientific Notation
_________________________________________________________
mega- M ,000,
kilo- k ,
deci- d
centi- c
milli- m
micro- m
nano- n

12. Significant figures ??? Method used to express accuracy and precision.
You can’t report numbers better than the method used to measure them.
67.20 cm = four significant figures
???
Certain
Digits
Uncertain
Digit

13. The number of significant digits is independent of the decimal point.
Significant figures
The number of significant digits is independent of the decimal point.
255
31.7
5.60
0.934
0.0150
These numbers
All have three
significant figures!

14. Rules for Counting Significant figures
Every non-zero digit is ALWAYS significant!
Zeros are what will give you a headache!
They are used/misused all of the time.

15. Rules for zeros Leading zeros are not significant. ???
Captive zeros are always significant!
three significant figures
Leading zero
???
4,008 - four significant figures
Captive zeros
???
Trailing zeros are significant …
IF there’s a decimal point in the number!
five significant figures
Trailing zero
???

16. Examples 250 mg \__ 2 significant figures 120. mileskg
23, s
\__ 7 significant figures

17. Significant figures: Rules for zeros
Scientific notation - can be used to clearly express significant figures.
A properly written number in scientific notation always has the proper number of significant figures.
= x 10-3
Three Significant
Figures

18. Significant figures and calculations
An answer can’t have more significant figures than the quantities used to produce it.
Example
How fast did you run if you
went 1.0 km in 3.0 minutes?
speed = 1.0 km
3.0 min
= 0.33 km
min

19. Significant figures and calculations
Multiplication and division.
Your answer should have the same number of sig figs as the original number with the smallest number of significant figures.
ONLY 3 SIG FIGS!
21.4 cm x cm = 66.2 cm2
135 km ÷ 2.0 hr = 68 km/hr
ONLY 2 SIG FIGS!

20. Significant figures and calculations
Addition and subtraction
Your answer should have the same number of digits to the right of the decimal point as the number having the fewest to start with. g g g
805.4 g g
83.7 g

21. Rounding off numbers
After calculations, you may need to round off.
If the first insignificant digit is 5 or more, you round up
If the first insignificant digit is 4 or less, you round down.

22. Examples of rounding off
If a set of calculations gave you the following numbers and you knew each was supposed to have four significant figures then -
becomes
becomes
1st insignificant digit

23. Examples of Rounding For example you want a 4 Sig Fig number
0 is dropped, it is <5
8 is dropped, it is >5; Note you must include the 0’s
5 is dropped it is = 5; note you need a 4 Sig Fig
780,582
1999.5
4965
780,600
2000.

24. Multiplication and division
 1.54 =
3.68  =
1.750  =
3.2650106  =
6.0221023  1.66110-24 =
107
49.7
46.4
1.586 107
1.000