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The scientific method consists of six interrelated
processes:
1.Observation of a phenomenon
 2. Develop a Question
3. Develop a Hypothesis (potential answer)
 4. Experimentation
 5. Data Analysis
 6. Conclusions
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Worked out:
Theory
Further
Experimentation
Didn’t work out:
New Hypothesis
Develop New
experimentation and
theory
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1. Observation
Ex.- a “magic” box seemingly producing more
water than possible
DATA: the result of a measurement or
observation
Ex.- mass of a sample, time for a reaction to
occur, temperature, length, volume
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QUALITATIVE DATA: general description (not
exactly measured or can’t be measured)
Ex.-color, odor, shape, texture, taste, smell;
bigger/smaller;
More?_____________________________
QUANTITATIVE DATA: answers “Exactly how
much/little/fast/slow/big/heavy/hot/cold?”
Ex.- pharmaceuticals (meds) development and
dosage; feed ratios and amounts for your
particular livestock; choke/brand/shell load for
the most uniform pattern/density to take down
whatever you are hunting;
More?_______________________________
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“Sheen” on water…
“Strong Petroleum” odor
“Stained” soils
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2. Formulation of a question
3. HYPOTHESIS:a proposed reason/answer for
what is observed that can be tested, an
“educated guess”
Observation of a phenomenon (something you
see happening) calls for some explanation. The
process of explaining observed behavior begins
with a hypothesis.
If the hypothesis survives extensive testing, it
may attain the status of either a:
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THEORY: tested by more experiments and
modified if necessary. A theory is considered
successful if it can be used to make predictions
that are true
Ex.- Einstein’s theory of relativity or the atomic
theory- a theory explains a broad principle of
nature that has been supported over time.
All theories are still subject to new experimental
data and can be modified/changed.
LAW: summarizes the results of many
observations and experiments
Ex.- Newton’s three laws of motion- If someone
skydives from a plane, they will always wind up
back at the Earth’s surface
4. EXPERIMENTATION:carefully designed testing
process to reinforce (yes) or refute (no) the
model system, the theory, or the hypothesis
 For the results of an experiment to be accepted,
anyone must be able to consistently produce
the same result by completing the experiment
as directed
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INDEPENDENT VARIABLE: what you change in an
experiment
Independent variable should be the ONLY condition
that affects the experiment’s outcome, everything
else should be identical and controlled.
Ex.- in an experiment to determine the amount of
yeast that will create the fastest rise in dough, the
amount of yeast would be the independent
variable.
DEPENDENT VARIABLE: changes in response to the
independent variable
Ex.-in an experiment to determine the amount of
yeast that will create the fastest rise in dough, the
height of the bread dough measured in the center
would be the dependent variable. (It depends on
the amount of yeast added).
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CONTROL OR CONTROL GROUP:the variable(s)
in an experiment that must stay the same to
eliminate false/misleading results
Ex.- in an experiment to determine the amount
of yeast that will create the fastest rise in
dough, the flour type/amount, sugar
type/amount, water temperature/amount, room
temperature/pressure, surface on which the
dough rises must all stay the same to be certain
that the amount of yeast is causing the
differences in height of dough.
Also, during experiment set-up and
completion, you MUST, MUST, MUST PREVENT
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CROSS-CONTAMINATION: indirect contamination
caused by contact with a contaminated source
Ex.- child with a severe peanut allergy that died
from kissing her boyfriend who had eaten some
peanut butter (or any food that doesn’t contain
an allergen, like peanuts, that has been on
equipment that processes peanuts and the nonpeanut food picks up peanut oils/dust, etc. that
cause the non-peanut food to cause a person
with a peanut allergy to react);equipment used
for testing/sampling that isn’t decontaminated
properly (water bailer and ungloved hands
examples)
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In an experiment or test, if you do not prevent
cross-contamination, YOUR RESULTS ARE NOT
VALID (RELIABLE)!!!!!
FYI It is an orange
peel not a lemon!!!!
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5. Data Analysis
ALWAYS THINK about your results, especially in
lab situations. Do they make sense? If not,
figure out why. Retest. Rethink your
controls/variables. What else might be
affecting your results (crosscontamination/another source)???
Ex.-Analytical results show contamination where
repeated testing has shown no contamination has
ever existed on a property. (email string Mrs. Ashcraft
showed us about a groundwater well that was being
reported as contaminated even though 10+ years of
data showed it had never been)
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6. CONCLUSION: a judgment based on the
information obtained in an experiment
MODEL: a drawing or 3-D representation of a
hypothesis, theory or law
Many hypothesis, theories and laws are
expressed with mathematical equations that
may confuse all but the best of mathematicians
(anyone watch the show “Numbers”??). Models
simplify complex ideas and provide a visual
image to help us process information.
Measurements are quantitative information.
They are more than just numbers, however. For
example, a cook could not communicate a
recipe by saying “Add 1 salt, 2 sugar and 3
flour.” Measurements report specific quantities
represented by common units. Nearly every
measurement is a number plus a unit.
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UNIT: a unit of measurement compares what is
to be measured with a previously defined
STANDARDIZED size. A unit defines the basic
quantity of mass, volume, time or other
quantity being measured.
Ex.- foot, inch, meter, pound, gram. A “foot
length” was used centuries ago to mark off
distances, but this system didn’t work as the
foot lengths were all different because
everyone’s feet were different. So, an
agreement was made on the standard “foot”
length and measuring implement’s (rulers) were
developed.
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Scientists all over the world have agreed
on a single measurement system called
The System of International Units,
abbreviated
SI.
This system was
adopted in 1960 by the General
Conference on Weights and Measures.
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More than 1
SI PREFIXES:are prefixes added to base units to
represent quantities that are smaller or larger
than the base unit
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ACCURACY: refers to the closeness of a set of
measurements to the actual/correct value of the
quantity measured
PRECISION: the degree of agreement between
multiple measurements (though they may not be
the correct value)
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PERCENTAGE ERROR: comparing the accuracy of
an individual value or average experimental
value quantitatively with the correct/accepted
value
Percentage error= Value experimental-Value accepted x
100
Valueaccepted
Ex.- The actual density of a certain material is
7.44 g/cm3. A student measures the density of
the same material as 7.30 g/cm3. The percent
error is found as follows:
Percentage error= 7.30 g/cm3-7.44g/cm3 x 100 = -1.9%
7.44g/cm3
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UNCERTAINTY: the degree of doubt in a single
measurement
Uncertainty is where SIGNIFICANT FIGURES, or
the number of meaningful digits, is applied. The
number of meaningful digits is determined by
the measuring device being used.
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SCIENTIFIC NOTATION: also referred to as
EXPONENTIAL NOTATION. It involves the
representation of a number as a power of ten.
Numbers are written in the form M x 10n, where the
factor M is a number greater than or equal to one (and
the correct amount of significant digits) but less than
10 and n is a whole number.
Ex.-2,300 can be written as 2.3 x 103 or 2.3 E103 (To
move the decimal in the scientific notation back to the
original number you would have to move it three places
to the right, so the exponent is “3”. Implied positive
signifies you are moving to the right or more positive.)
0.0023 can be written as 2.3x10-3 or 2.3 E10-3(To move
the decimal in the scientific notation back to the original
number you would have to move it three places to the
left, so the exponent is “-3” Negative signifies you are
moving to the left or more negative.)
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Rule: to convert a number to scientific
notation, the original decimal point is moved
to the left or right so that the final number
includes one digit to the left of the decimal
followed by however many digits to the right
necessary to achieve the correct amount of
significant digits followed by the exponent
signifying the number equal to the number of
places from which the original decimal was
moved. (see examples)
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Mathematical Operations using Scientific Notation
1. Addition and Subtraction:
Values (n factor/exponent) must be the same. If
they are not, adjustments must be made to the
values so that all exponents are equal. Once
exponents are equal, the M factors can be added or
subtracted.
Ex.- 4.2x104 kg + 7.9x103 kg
1. Adjust to make exponents equal, so
4.2 x104kg
+
.79x104kg
4.99x104 kg
2. Then just add, keeping exponent as is
3. Check significant digits. This should only have 2,
as your original measurements only had two, so
round to two significant digits.
FINAL ANSWER= 5.0x104kg
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2. Multiplication:
The M factors are multiplied and the exponents
are ADDED algebraically (following integer rules
for addition).
Ex.- (5.23x106mm)(7.1x10-2mm)=
1. multiply 5.23x7.1= 37.133
2. adjust to correct significant digits, so 37
3. add exponents 6+(-2), so 4
4. put it all together, so 37x10437x104mm2(don’t
forget, when multiplying, the unit will also be
squared or cubed)
5. record in correct scientific notation format, so
FINAL ANSWER is 3.7x105mm2
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3. Division:
The M factors are divided and the exponent of the
denominator is SUBTRACTED algebraically
(following integer rules for subtraction)from the
exponent of the numerator.
Ex.- (5.23x106mm)/(7.1x10-2mm)=
1. 5.23/7.1= .73661972
2. adjust to correct significant digits, so .74
3. subtractdenominator exponent from numerator
exponent 6-(-2) [remember, when subtracting
integers, you ADD it’s opposite], so it is actually
6+2=8
4. put it all together, so .74x108
5. record in correct scientific notation format, so
FINAL ANSWER is 7.4x107
 CHEMISTRY:The
study of the
composition, structure and
properties of matter and the
changes it undergoes
including the energy changes
that accompany those
changes.
CHEMICAL: any substance that has a
definite composition
 Therefore, ALL matter—living and
nonliving, natural or artificial —has a
chemical basis. A common
misconception exists that any
“chemical” is artificial or unnatural.
 MATTER: anything that has mass and
occupies space.
 ENERGY: The ability to do work to
accomplish some change.
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There are three main states of Matter:
SOLID: consists of particles that are close together
and have a regular and predictable pattern of
particle arrangement (crystalline). A solid has both
fixed volume and fixed shape. Solids have very
strong attractive forces and are fixed in position
compared to liquids and gases.
LIQUID: consists of particles closer together than in
a gas and has a definite volume but no definite
shape—it takes the shape of its container. Liquid
molecules can flow around each other.
GAS: consists of particles that are widely separated
and has no definite shape—it will expand to fill any
container.
Note- Gases are still considered “fluids”, as they
have the ability to flow.
 An
important fourth state of matter
is known as PLASMA: a high
temperature physical state of
matter in which atoms lose most of
their electrons, particles that make
up atoms.
 Ex.-
Plasma is found in fluorescent
light bulbs and stars
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All matter can have chemical and physical
properties:
CHEMICAL PROPERTY: relates to a substance’s
ability to undergo changes that TRANSFORM it
into DIFFERENT substances
Ex.- The ability of a substance (wood/charcoal,
etc.) to burn
PHYSICAL PROPERTY: can be observed or
measured without changing the identity of the
substance
Ex.- melting point, boiling point (not the same
as catching something on fire), freezing point
A CHANGE OF STATE is a physical change of a
substance from one state to another.
Change of
State
Process Name
Example
Solid--Liquid
Melting
Ice--Water
Solid-- Gas
Sublimation
Dry Ice—CO2 Gas
Liquid-- Solid
Freezing
Water--Ice
Liquid--Gas
Vaporization
Gas--Liquid
Condensation
Gas--Solid
Deposition
Water—Water
Vapor
Water Vapor-Water
Water Vapor--Ice
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DENSITY: a characteristic physical
property of a substance that is the ratio
of mass to volume
Density= mass or D=m
volume
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V
Objects/substances with more density
will sink in objects/substances with less
density.
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MASS: a measure of the amount of matter
(physical property). Mass is measured using a
balance (scale).
NOTE: Mass and weight are not the same.
Mass is determined by comparing the mass of
an object with a set of standard masses that
are part of the balance and does not change.
Whereas, ….
WEIGHT: is a measure of the gravitational pull
on matter.
Weight will change depending on the force of
gravity on an object.
 VOLUME:
the amount of space
occupied by an object
 CHEMICAL CHANGE/REACTION: one
or more substances are converted
into different substances
 Ex.-
rusting iron (iron combines
with oxygen in the air); metal
corrosion because of acid rain
 PHYSICAL
CHANGE: a change in a
substance that does not involve a
change in the identity of the
substance
 Ex.-
grinding, cutting, melting and
boiling something (a material)
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The boundaries between physical and
chemical changes aren’t always clear.
For example, while most chemists
would consider the dissolving of
sucrose (a sugar) into water to be a
physical change, many chemists would
consider dissolving table salt in water
as a chemical change.
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ATOM: the smallest unit of an element that
maintains the chemical identity of that element.
ELEMENT: pure substance that cannot be broken
down into simpler, stable substances and is
made of one type of atom. It can have one or
more atoms of the same kind.
Ex.- Carbon. Carbon is an element containing
one kind of atom. All discovered elements are
represented on the periodic table.
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COMPOUND: a substance that can be broken
down into simple stable substances. Each
compound is made of the atoms of two or more
elements that are chemically bonded.
Ex.- Water. Water is made of two elements,
hydrogen and oxygen.
MIXTURE: is a blend of two or more kinds of
matter, each of which retains its own identity
and properties (physical change)
Ex.- air that we breathe is a mixture of gases
and particulate matter, sweet tea, wood, blood
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HETEROGENEOUS MIXTURE: a mixture
that is not uniform throughout (“hetero”
= “different”—remember heterozygous
traits from Biology [Rr]?)
Ex.- a tossed salad, no bake cookies,
blood
HOMOGENEOUS MIXTURE: a mixture that
is uniform throughout, also known as
SOLUTIONS(“homo” = “same”--remember homozygous traits from
Biology [rr]?)
Ex.-sweet tea, chocolate milk