1. Units and data EQ: What is the correct format for numbers in scientific notation? How are numbers converted using the metric system? How are significant figures counted?

2. Standard Notation to Scientific Notation
Positive exponent: Number ≥ 1
Negative exponent: Number ≤ 1
Exponent = Number of times the decimal is moved
Only 1 non-zero number in front of decimal
Ex: 1,

3. Scientific Notation to Standard Notation
Positive exponent: move decimal to the right
Negative exponent: move decimal to the left
Ex: 3.65 x 104
2.12 x 10-3

4. Practice

5. SI base Units
Quantity
Base Unit
Time
Seconds (s)
Length
Meter (m)
Mass
Kilogram (kg)
Temperature
Kelvin (K)
Amount of a substance
Mole (mol)
Electric current
Ampere (A)
Luminous Intensity
Candela (cd)
Note: ˚C = Kelvin (K) or Kelvin (K) – = ˚C

6. Metric Conversions
Gee Man…kingwood High does [math, Language, grammer] during class monday…maybe naps! Giga Mega…kilo Hecta deca [meter, Liter, gram] deci centi milli…micro nano! … Units …

7. Practice 35 mm = ____ cm 17649.3 cm = ____Mm
14,443 L = ____ kL 1.9 mL = _____nL
kg = ____ g 16 mm = ____ km
35.4 L = ____ dL kL = ____ mL

8. Dimensional Analysis
All other unit conversions can be made through dimensional analysis, which uses conversion factor to switch between units.
Conversion factors are simply the equivalence of one unit to another.
Ex. 1 min = 60 sec or 1 meter = 3.28 feet
1st: Put the number in the problem over 1
2nd: Determine a conversion factor
3rd: Apply conversion factor so units are the same diagonally (reading from left to right)

9. Practice: 18.77 g to mg 37.4 cm to m 4.7 days to sec
956,765 hours to weeks

10. Sig Figs measure the degree of precision of a
Significant Figures
Sig Figs measure the degree of precision of a
measurement.

11. Rules for counting sig figs:
There are ONLY two rules to
remember when counting
the # of Sig Figs.

12. Rule #1: Don’t start counting till you get to a number that isn’t a zero. Rule #2: Once you start counting, don’t stop till you’ve counted all the digits, including zeroes.

13. And you need to remember a little geography:
Where is the Atlantic Ocean, and where is the Pacific Ocean?
Decimal is Present:
Start counting from the first non-zero number from the Pacific (left) side.
Decimal is Absent:
Start counting from the first non-zero number from the Atlantic (right) side.

14. Examples
2.55
3 S.F.
0.2500
4 S.F.
5 S.F.
100.25

15. Examples
135
3 S.F.
100
1 S.F.
3 S.F.
10500

16. Examples
350
0.0020
17,500
27.02
2060
135.0

17. Rounding
Starting from the left find the 1st nonzero number….this is the MOST significant digit, then round accordingly
Numbers BEFORE decimal = convert to zero
Numbers AFTER decimal = Drop
EXAMPLE: round to 2 sig figs
120,320
Now round each to 3 sig figs

18. Using sig figs in calculations

19. For multiplication and division:

20. Your answer should have the fewest number of significant figures from the problem

21. x =
5 S.F.
1 S.F.
4 S.F.?
Answer must be recorded as 50,000 cm2
It can have only one sig fig.

22. What is the correct answer?
610 x 6.20 = 3782
2 S.F.
3 S.F.
3800
What is the correct answer?

23. Example: You calculate the density of an object with mass of 24
Example: You calculate the density of an object with mass of grams, and volume of 62.5 ml. How many sig figs in your answer? Density=mass/volume /62.5 = Correct Sig. Figs. = 0.389

24. For addition and subtraction

25. Your answer can not contain more decimal places than the least precise measurement.

26. Line up the decimal points in the numbers.
=????

27. 2.515
1.3
15.815
Answer stops here

28. Calculations & Sig Figs Recap
Multiplication & Division
Fewest Number of Significant figures
Addition & Subtraction
Fewest Numbers after the decimal (least precise)

29. Sig Figs & Scientific notation

30. The number of sig figs comes from the number written before the times sign.

31. Examples
3.50 x 1023
3 S.F.
5.0 x 10 -4
2 S.F.
1 S.F.
3 x 10-4

32. Density Physical property of matter Measure of mass per unit volume
g/L or g/cm3
1 mL = 1 cm3
Ex. What is the density of a metal that is 37.2 cm3 and weighs g?
How many numbers should your answer have? Why?

33. Application: % Error % Error = experimental – theoretical x 100
Example: As the result of experimental work, a student finds the density of a liquid to be g/cm3. The known density of that liquid is g/cm3. What is the percent error of this student’s work?
Practice: The melting point of potassium thiocyanate determined by a student in the laboratory turned out to be oC. The accepted value of this melting point is oC. What is the percent error in this reading?