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SCIENTIFIC METHOD
1. FACT : An observable event; indisputable evidence which does
not explain but simply is.
2. HYPOTHESIS: A guess to try to explain an observation.
3. EXPERIMENT: A systematic exploration of an observation or
concept.
4. THEORY: An explanation of the facts; it can be proven by
experiment and it confirms an hypothesis.
5. LAW: A theory which has undergone rigorous experimentation
and no contradiction can be found.
Note:
MODEL: A visual or mathematical device or method used to demonstrate a
theory or concept.
Scientific Method
Observation of an event or object
A question
A Hypothesis
Experimentation
Theory
New hypothesis
further experimentation
Developement of new
experimentation and theory
LAW
EXPERIMENTS
In ancient Greece philosophers, like Aristotle,
did very little physical experimentation. Mental
exercises were the preferred method for solving
problems.
SCIENTIFIC METHOD depends on
experimentation therefore the ability to make
measurements is vital when using scientific
method.
ACCURACY vs. PRECISION

Accurate & precise

inaccurate & imprecise
inaccurate but precise
MEASUREMENTS
Significant Figures
1. All nonzero numbers are significant figures.
2. Zero’s follow the rules below.
Zero’s between numbers are significant.
30.09 has 4 SF
Zero’s that precede are NOT significant.
0.000034 has 2 SF
Zero’s at the end of decimals are significant.
0.00900 has 3 SF
Zero’s at the end without decimals are ambiguous.
4050 has either 4 SF or 3 SF
MEASUREMENTS
Significant Figures & Calculations
Significant figures are based on the tools used to make the
measurement. An imprecise tool will negate the precision of the other
tools used. The following rules are used when measurements are
used in calculations.
Adding/subtracting
The result should be rounded to the same number of
decimal places as the measurement with the least decimal
places.
Multiplying/dividing
The result should contain the same number of
significant figures as the measurement with the least
significant figures.
MEASUREMENTS
Significant Figures & Calculations
Adding/subtracting
345.678
+ 12.67
0.07283
-0.0162789
358.35
0.05655
Multiplying/dividing
12.0340 x 3.98 =
98.657 / 43 =
2.3
47.9
MEASUREMENTS
Scientific Notation
Many measurements in science involve either very large
numbers or very small numbers (#). Scientific notation
is one method for communicating these types of
numbers with minimal writing.
GENERIC FORMAT:
# . # #… x 10#
A negative exponent represents a number less than 1
and a positive exponent represents a number greater
than 1.
6.75 x 10-3 is the same as 0.00675
6.75 x 103 is the same as 6750
MEASUREMENTS
Scientific Notation
Give the following in scientific notation (or write it out)
with the appropriate significant figures.
1. 528900300000 = 5.289003 x 1011
-12
2. 0.000000000003400 = 3.400 x 10
3. 0.23 =
2.3 x 10-1
4. 5.678 x 10-7 = 0.0000005678
5. 9.8 x 104 =
98000
PRACTICE PROBLEMS #1
Show your work for the following questions on the back. Always give the
correct significant figures.
1. Express each of the following numbers in scientific notation & 3
significant figures.
-3
9
8.77
x
10
3.45
x
10
A) 3445490087
_______
C) 0.008768 _______
-7
8.24
x
10
B) 0.0000008243 _______
4
2.36
x
10
D) 23560
_______
-4
4.98 x 10
2. 0.003496 - 0.002998 = ________________
-2
3.56
x
10
3. (4.36-5.62) / (32.98 + 2.4) = ______________________
1.1 x 10 -10
4. 8.453 x 10- 43 / 7.7 x 10-33 = ________________
5. [(56.7 x
10-6)
(32 x
1011)]5
/ (5.6 x
1017)1/2
32
2.6
x
10
= __________
GROUP STUDY PROBLEM #1
Show all work for the following questions on the back page. Always give the correct
significant figures.
1. What is the scientific method?
2. Describe the difference between accuracy and precision.
3. Explain why tasting chemicals during an experiment is not a safe
practice?
4. Express each of the following numbers in scientific notation.
a) 0.0404
_______
b) 0.0081 _______
c) 40.0
_______ d) 2900000 _______
e) 0.0000055 _______ f) 40300
_______
6. (452 x 6.2) / 14.30 = ______________________
7. 98.78564 - 97.9299 = ________________
8. 6.022 x 1023 / 1.9 x 10-19 = ________________
9. ( 0.3 - 0.09) / (4.3 x 10-3 + 7.232 x 10-4) = ____________
10. [(2.4 x 1012) (5.78 x 10-31)]3 / (2.965 x 1014)1/2 = __________