Matter and Change
What is Chemistry All About?
How does this photo illustrate what chemistry is all
about??
 Chemical reactions of rusting/weathering/maybe a
fire in the fireplace
 Physical states of water
 Different types of materials: glass, wood, living
material, brick, snow
The Study of Matter
and Change
What is Matter?
 Anything that has
mass and takes up
space (volume)
Not Matter
 Light
 Energy
 Emotions or Feelings
 Thoughts
 Electricity
 Sound
Pure Science Vs Applied Science
 Pure Science: For the sake of the knowledge
 Studying butterflies just to know more
 Researcher lives on a remote island to daily study the
jungle trees
 Studying ape behavior
 Applied Science: Using science to solve a particular
problem
 Scientist studying corn in fields to increase the yield for
farmers
 Scientist searching for a cancer cure
Why is Pure Research Important?
 A Base of knowledge when needed
 Keeps us current
 General not specific and possible commercial
 Accidental Discoveries
Technology
 Application of Science for human benefit
 Good and Bad
 Nuclear Technology
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Good: Energy
Bad: Waste
 Computer Technology
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Good: Communication Bad: Wasted Time
Chemistry is traditionally broken into branches
that focus on specific areas such as
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Organic chemistry
Inorganic chemistry
Physical chemistry
Analytical chemistry
Biochemistry
Environmental chemistry
Industrial chemistry
Polymer chemistry
Theoretical chemistry
Thermochemistry
This Class
HS General Chemistry is Inorganic
 Inorganic: the study of non-carbon based compounds
 Organic Chemistry: Study of matter that contains
carbon
The Scientific Method
 The scientific method is a systematic approach used
in scientific study, whether it is chemistry, physics,
biology, or another science.
 To solve problems
 Not a set of rigid steps
 It is an organized process used by scientists to do
research, and provides methods for scientists to verify
the work of others.
Observations
 Gathering Information (Data) using the five senses
 No trivial or unimportant observations
 Don’t make inferences or assumptions when you observe
– Qualitative data is obtained through observations
that describe color, smell, shape, or some other
physical characteristic that is related to the five
senses.
– Quantitative data is obtained from numerical
observations that describe how much, how little,
how big or how fast.
Controlled Experiment
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A test of a hypothesis
Making observations under controlled conditions
Where only one variable at a time is changed
Systematic approach to test a hypothesis
Parts of An Experiment
 Variables: A condition changed in an experiment
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Independent
Dependent
 Constants: any factor not changed in an experiment
 Control: Group/set up that has no changes made to it
 Conclusion: A judgment based on the observations made in a
controlled experiment
Independent Variable
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Changed by the experimenter
Allowed to change
The Cause in Cause and Effect
Manipulated Variable
Happens First
 The water’s temperature increased as more heat was
applied.
 The temperature of the solid caused the density of the
solid to change
 An increase in phosphorous helped the plants to grow
taller.
Dependent Variable
 Changes in response to the change in the independent
variable
 Responding Variable
 Happens second
 The boiling point increased as salt was added to the
water
 The hamster grew two inches with an increase in the
hormone.
Control
 A point of comparison in an experiment
 The group that does NOT receive the treatment
Constants
 Specifics that remain the same between the control
group and the experimental group
 Only the independent variable should be changed by
the experimenter
Examples of Constants:
Conclusion
 A conclusion is a judgment based on the information
obtained from the experiment
Hypothesis and Experiment
 Hypothesis: A tentative explanation of observations
 A tentative answer
 A statement to be tested by an experiment
Example: If I give the fish more hormone then they will
grow longer.
 Experiment: The test of a hypothesis
 A controlled set of steps to test a hypothesis
Theory Vs Hypothesis
 A theory is a hypothesis that has stood the test of
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repeated experiments
An explanation of results
Never proven
Can be disproven
All theories are hypotheses . (True)
All hypotheses can become theories. (True)
All hypotheses are theories. (False)
Experiment
 Kate noticed that she could dissolve more sugar in the tea when it was
warm than when it was ice cold. She wondered if this was true for all
solids. She decided to design an experiment to see if water temperature
effects how much salt can be dissolved.
 She chose table salt as her solid to test. She used water as her solvent.
 Hypothesis: An increase in the temperature of the water will allow
more salt to dissolve,
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She placed 100 mL of water in each of 10 250 mL beakers.
She cooled the water in beaker # 1 to 10 degrees C.
The water in beaker #2 was 25 degrees C.
Beaker # 3 water was heated to 35 degrees C.
Beaker # 4 water was heated to 45 degrees C.
Beaker # 5 was heated to 55 degrees C.
 Beaker # 6 65 degrees C
 Beaker # 7 75 degrees C
 Beaker # 8 85 degrees C
 Beaker # 9 95 degrees C
 Beaker # 10 100 degrees C
 She added salt to each beaker while using a magnetic
stirrer which provided constant and uniform stirring
until no more salt would dissolve.
 She measured and recorded the amount of salt that
dissolved in each beaker.
 Her data is shown below.
Data
Amount of water
100 mL
Temp of Water
(degrees C)
Grams of salt
dissolved
1
10
37
2
25
37
3
35
38
4
45
38
5
55
38
6
65
38
7
75
39
8
85
40
9
95
40
10
100
40
Identify the following
 Independent Variable
 Dependent Variable
 Control
 Constants
 Possible conclusion
 Another hypothesis
Scientific Law Vs Theory
 Observable Fact
 Explanation
 True: Always observed
 Tentative
 No known exceptions
 Can be disproven
 No explanation
Development of a Theory
 Start with an observation that evokes a question: Broth spoils when I
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leave it out for a couple of days. Why?
Using logic and previous knowledge, state a possible answer, called a
Hypothesis: Tiny organisms floating in the air must fall into the broth
and start reproducing.
Perform an experiment or Test: After boiling some broth, I divide it into
two containers, one covered and one not covered. I place them on the table
for two days and see if one spoils. Only the uncovered broth spoiled.
Then publish your findings in a peer-reviewed journal. Publication:
"Only broth that is exposed to the air after two days tended to spoil. The
covered specimen did not."
Other scientists read about your experiment and try to duplicate it.
Verification: Every scientist who tries your experiment comes up with the
same results. So they try other methods to make sure your experiment was
measuring what it was supposed to. Again, they get the same results every
time.
In time, and if experiments continue to support your hypothesis, it
becomes a Theory: Microorganisms from the air cause broth to spoil.
Useful Prediction: If I leave food items open to the air, they will spoil. If I
want to keep them from spoiling, I will keep them covered.
Chemistry is Central to our Lives
 Chemistry is about composition, structure, function,
and interaction of matter
 Everything has composition, structure, function, and
interaction.
 All other sciences (biology, physics, geology, etc) have
their basis in chemistry
Mass Vs Weight
Mass
Weight
 Not influenced by gravity
 Affected by gravity
 Changes only when amount
 W = mg
of matter changes
 Kilograms or grams
 g= 9.8 m/s2
Your Mass
Earth
Moon
 M ass = 60 kg
 Gravity = 1/6th the gravity on
Earth
 Mass = 60 kg
 Not affected by gravity
Weight
Earth
Moon
 m = 60 kg
 m = 60 kg
 W = mg
 W = mg
 W = (6o kg)(9.8m/s2)
 g = 9.8m/s2/6 = 1.63 m/s2
 W = 588 Newtons
 W = (60 kg)(1.63m/s2)
 W = 98 Newtons
Environment with No Gravity
 Weight only would change
 You would weigh less
 Amount of Matter is not affected
 Mass stays the same
Submicroscopic and Macroscopic
Submicroscopic
Macroscopic
 Atomic Level
 What we observe
 What happens here
 Determined by the
determines the macroscopic
submicroscopic (atomic)
 Chemist are interested in
how the atomic level
determines the macroscopic
Substance is matter that has a definite
composition. Also known as a chemical
Element
 One type of atom
 Oxygen (O2)
 Ozone (O3)
 Copper
Compound
 Two or more types of atoms
 Sodium chloride (table
salt) NaCl
 Ethyl alcohol
 H2O
Chance Discoveries
 Discoveries made by accident
 Not trying to find an answer
 Examples
 Velcro
 Penicillin
 Teflon
 Chocolate Chip Cookies
 The Microwave Oven
 Artificial Sweeteners
 Curiosity Drives Discovery