EXACT NUMBERS!
Numbers determined by counting
or by definition
Ex: 6 apples, 1 teacher
1 inch=2.54 cm
IN SCIENCE…
Numbers are based on
MEASUREMENTS made in the lab.
Our data is only as good as the
measurements we make and the
instruments we use.
QUALITATIVE DATA
Observation that DOES NOT involve
a number/measurement
EX. Presence of odor, color change
QUANTITATIVE DATA
Observation that DOES involve a
number/measurement (has
magnitude size or amount)
Ex. Length, mass, volume
COPY IN YOUR NOTES!!
Accuracy: how close a measured value is to
the actual (true) value.
Precision: how close the measured values
are to each other.
ACCURACY VS. PRECISION
SIGNIFICANT FIGURES
• Shows how PRECISE a measurement is
• Indicates the QUALITY of the instrument
you use (how sensitive or exact)
EX. Graduated cylinder vs. beaker
SIG FIG RULES!
COUNTING SIGNIFICANT FIGURES
5432.1
0.00032
4004
82.0000
5 sig figs
2 sig figs
4 sig figs
6 sig figs
10
SCIENTIFIC NOTATION
Used to write really LARGE or
really small #’s
Why? To save space & time
SCI. NOTATION RULES!
Written in the form of m x 10n
m: ≥ 1 AND <10
indicate the number of sig. figs
STEPS OF THE SCIENTIFIC NOTATION
Step 1) Determine the sig figs
106,000,000 = 3 sig figs
Step 2) Determine the value of M using the sig figs
1.06 (remember this must be between 1 and 10)
Step 3) Add the 10’s multiplier
1.06 x 10n
Step 4) Determine the value of “n” by counting the number of
times you move the decimal in the original number to get
the value for “M”
Step 5) Determine the sign of “n” by looking at the direction
that you moved the decimal
 Move decimal to left = “n” is positive
 Move decimal to right = “n” is negative
NOW GO THE OTHER WAY!!
Ex. 1) 7,801
Ex. 2) 0.00030
7.801 x 103
3.0 x 10-4
15
Ex. 1) 3.1 x 104
Ex. 2) 4.08 x 10-6
31,000
0.00000408
16
SI UNITS OF MEASUREMENT
One system for all scientists around the world
We must have a standard for comparison
length – meter (m)
mass – kilogram(kg)
time – second (s)
volume – liter (L)
SI PREFIXES
Added to base units to represent large or smaller quantities
SI Prefix
Unit Abbreviation
Exponential Factor
kilo
K
103
hecto
h
102
deka
da
101
BASE
m,g,s,L
100
deci
d
10-1
centi
c
10-2
milli
m
10-3
King Henry Died By Drinking Chocolate Milk
EXAMPLE
10,000
10 g = ____________mg?
K h da b d c m
EXAMPLE
14.6 dL= __________ kL