Numbers that are extremely large can be
difficult to deal with…sooo
Scientists convert these numbers into scientific
notation
Scientific notation expresses numbers as a
multiple of two factors:



1.
2.
A number between 1 and 10 (only 1 digit to the left of the
decimal!)
Ten raised to a power
For example:
A proton’s mass =0.0000000000000000000000000017262 kg
If you put it in scientific notation, the mass of a
proton is expressed as 1.7262 x 10-27 kg
Remember:
When numbers larger than 1 are expressed in
scientific notation, the power of ten is positive
When numbers smaller than 1 are expressed in
scientific notation, the power of ten is negative
Try these:
Convert 1,392,000 to scientific notation.
= 1.392 x 106
Convert 0.000,000,028 to scientific notation.
= 2.8 x 10-8
Make sure the exponents are the same!!
7.35 x 102 + 2.43 x 102 = 9.78 x 102
•
If the exponents are not the same, you have to make
them the same!!
•
Tip: if you increase the exponent, you decrease the
decimal ----- if you decrease the exponent, you increase
the decimal
•
Example:
Tokyo pop: 2.70 x 107
Mexico City pop: 15.6 x 106 = 1.56 x 107
Sao Paolo pop: 0.165 x 108 = 1.65 x 107
NOW you can add them together and carry thru the
exponent
Total= 5.91 x 107
•

Multiplication:

Multiply decimals and ADD exponents
 Ex : (1.2 x 106) x (3.0 x 104) = 3.6 x 1010
 * Ex: (1.2 x 106) x (3.0 x 10-4) = 3.6 x 102

6 + 4 = 10
6 + (-4) = 2
Division:

Divide decimals and SUBTRACT exponents
 Ex: (5.0 x 108) ÷ (2.5 x 104) = 2.0 x 104
 *Ex: (5.0 x 108) ÷ (2.5 x 10-4) = 2.0 x 1012
8–4=4
8 – (-4) = 12

SI units: Systeme Internationale d’ Unites

standard units of measurement to be understood by all scientists



Base Units: defined unit of measurement that is
based on an object or event in the physical
world
there are 7 base units
some familiar quantities are time, length, mass, and temp
Time



second (s)
Many chemical reactions
take place in less than a
second so scientist often add
prefixes, based on multiples
of ten, to the base units.
ex. Millisecond
Length





meter (m)
A meter is the distance that
light travels though a
vacuum in 1/299 792 458 of a
second.
What is a vacuum?
Close in length to a yard.
Prefixes also apply…ex.
millimeter
Mass





mass is a measurement of matter
kilogram (kg)
about 2.2 pounds
Masses measured in most
laboratories are much smaller
than a kilogram, so scientists use
grams (g) or milligrams (mg).
How many grams are in a
kilogram?


1000
How many milligrams are in a
gram?

1000



Not all quantities are measured in base units
A unit that is defined by a combination of base
units is called a derived unit.
Volume and Density are measured in derived
units.
Volume
 The space occupied
by an object
 Unit = cm3 = mL
 Liters are used to
measure the amount
of liquid in a
container (about the
same volume as a
quart)
 Prefixes also
applied…ex.
milliliter
Quantity
Base Unit
Time
Second (s)
Length
Meter (m)
Mass
Kilogram (kg)
Temperature
Kelvin (K)
Amount of a substance
Mole (mol)
Electric current
Ampere (A)
Luminous intensity
Candela (cd)
Prefix
Symbol
Numerical Value
in Base Units
Power of 10
Equivalent
Giga
G
1,000,000,000
109
Mega
M
1,000,000
106
Kilo
K
1000
103
--
--
1
100
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
Pico
p
0.000000000001
10-12