1
More Preliminaries
Scientific Method
Metric System
Uncertainty
Complex sig figs
●
What if it uses both addition and
multiplication rules?
●
Round when you change rules.
9.23
8.4
4.53
1.882

×
=
(
2.5
1.8
(3.3
2.7)
×
+
×
=
Scientific method.
●
A way of solving problems
●
Observation what is seen or measured
●
Hypothesis educated guess of why
things behave the way they do.
(possible explanation)
●
Experiment designed to test hypothesis
●
leads to new observations,
●
and the cycle goes on
Scientific method.
●
After many cycles, a broad, generalizable
explanation is developed for why things
behave the way they do
●
Theory
●
Also regular patterns of how things
behave the same in different systems
emerges
●
Law
●
Laws are summaries of observations
●
Often mathematical relationship
Scientific method.
●
Theories have predictive value.
●
The true test of a theory is if it can
predict new behaviors.
●
If the prediction is wrong, the theory
must be changed.
●
Theory why
●
Law – how
●
Law – equation of how things change
Observations
Hypothesis
Experiment
Law
Theory
(Model)
Prediction
Experiment
Modify
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2
Metric System
●
Every measurement has two parts
●
Number
●
Scale (unit)
●
SI system (le Systeme International)
based on the metric system
●
Prefix + base unit
●
Prefix tells you the power of 10 to
multiply by  decimal system easy
conversions
Metric System
●
Base Units
●
Mass  kilogram (kg)
●
Length meter (m)
●
Time  second (s)
●
Temperature Kelvin (K)
●
Electric current ampere (amp, A)
●
Amount of substance mole
(mol)
Prefixes
●
giga
G
1,000,000,000 10
9
●
mega 
M
1,000,000
10
6
●
kilo 
k
1,000
10
3
●
deci
d
0.1
10
1
●
centi
c
0.01
10
2
●
milli
m
0.001
10
3
●
micro
μ
0.000001
10
6
●
nano
n
0.000000001
10
9
Deriving the Liter
●
Liter is defined as the volume of 1
dm
3
●
gram is the mass of 1 cm
3
Mass and Weight
●
Mass is measure of resistance to
change in motion
●
Weight is force of gravity.
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 Spring '08
 FREEMAN
 Chemistry, International System of Units, Kilogram, Chemical compound

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