Numbers in Chemistry
Ch. 3 Sect. 2-3
Qualitative vs. Quantitative
Write an example of a quantitative observation that you
make at home or at school.
Metric Base Units
Quantity
Unit
Unit Symbol
Length
Mass
Time
meter
kilogram
second
m
kg
s
Temperature
Volume
Amount of a
substance
Kelvin
Liter
K
L
mole
mol
Prefixes for Metric Base Units
Prefix
Symbol
Meaning
Mega-
M
million
kilo-
k
thousand
deci-
d
tenth
centi-
c
hundredth
milli-
m
thousandth
micro-
μ
millionth
nano-
n
billionth
pico
p
trillionth
Metric Conversions
Move decimal to the left
M
k
1 d cm
μ
Move decimal to the right
n
p
Dimensional Analysis
1. Write down given measurement.
2. Setup a conversion factor.
3. Cancel units.
4. Calculate answer:
1. Multiply by each number on the top.
2. Divide by each number on the bottom.
Scientific Notation
Base must be between 1 and 10:
45,000,000,000,000 = 4.5 x 1016
2.641 x 1012 = 2,641,000,000,000
0.00000000000000378 = 3.78 x 10-15
Scientific Notation Calculations
Multiply = add exponents
Divide = subtract exponents
Add/Subtract = convert to same exponent
Skills Practice 1
1.
2.
3.
4.
5.
6.
7.
9,434,880 mL
17.8 cases
0.333 cases
a) 0.156 m; b)4 x 1010 μg; c) 92,000 μg; d) 91,600 nm
a) 2.229 x 107; b) 8.07 x 106; c) 5.41 x 1020; d) 1.12 x 107
a) 2.300021 x 1010; b) 3.5 x 10-9
a) 235,400; b) 0.000000003400