Chem 400 Chapter 1 Lecture Notes Part 2
Measurements, Metric System, SI Units, and Scientific Notation
• In the lab, we make measurements, that is we collect data with numbers and units.
• The basic types of measurements with simple units are _________, __________, ________,
__________, __________, ____________, and _____________.
• Although there are many different ways of expressing these measurements, there is an approved
system of units, the SI system. That way, any scientist can communicate with and understand the
measurements that any other scientist makes.
Here is a table of these measurements, the SI system, and our US system.
Measurement
SI Unit and abbreviation
US Unit and abbreviation
• To go between very small numbers and large numbers, we use the metric system of prefixes:
Prefix Abbreviation Math Meaning
Example
giga
G
1x10
9
or 1,000,000,000
1GW = 1x10
9
W
mega
M
1x10
6
or 1,000,000
1Mm = 1x10
6
m
kilo
k
hecto
h
deka
da


1 (Base Unit)

deci
d
centi
c
milli
m
micro
μ
nano
n
pico
p
femto f
1x10
15
or 0.000 000 000 000 001
*Memorize the bolded ones. Fill in the blanks.
• Another way to express large or small numbers without using prefixes is by scientific notation
(regular number format is actually called floating notation).
• Scientific notation is a type of exponential notation where there is exactly 1 digit to the left of the
decimal.
• Write the following numbers in scientific notation:
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View Full Document• Important Note: Almost all numbers in chemistry have units! Remember this: numbers without
units are garbage!
• Mass and Weight:
• What’s the difference between mass and weight!
• Although they are different, and we truly measure mass in the lab, it is very common to say the
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 Fall '06
 Dr.Samples
 International System of Units, SI prefix, Kilogram, Sig Figs

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