Chemistry 101
Vandan Desai
P a g e

1
Chapter 3: Measurement
(Lecture Outline)

I.
Measurements are quantitative observations
A.
Observations can be
qualitative
or
quantitative
:
1.
Qualitative
observations are nonnumerical; they ask “
what
”
2.
Quantitative
observations are numerical; they ask “
how much
”
B.
Measurements:
1.
Always involve a comparison
2.
Require units
3.
Involve numbers that are inexact
(numbers in mathematics are exact
)
4.
Include uncertainty
(
error
) due to the inherent physical limitations of the
observer and the instrument used (to make the measurement)
II.
Measurements always include units
A.
Chemists use SI units
for measurements, which are based on the
metric system
B.
All SI units are based on a set of
seven
measured base units
:
Measurement
Unit
Symbol
Length
meter
m
Mass
gram
g
Time
second
s
Electric Current
ampere
A
Temperature
Kelvin
K
Amount of Substance
mole
mol
Luminous Intensity
candela
cd
C.
Derived units
involve a combination of base units, including
D.
Base units are frequently
too large
or
small
for a measurement
E.
Decimal multipliers
are used to adjust the size of base units, including:
1.
mega = 10
6
, kilo = 10
3
2.
deci = 10
1
, centi = 10
2
, milli = 10
3
, micro = 10
6
, nano = 10
9
, pico = 10
12
F.
You may encounter
nonSI metric system units
, including:
G.
English and Metric units are related using
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 Spring '08
 TaraCarpenter
 Chemistry, International System of Units, Vandan Desai

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