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The Scientific Method
Scientific Method
• Scientific Method• Scientific Law• Scientific Method and Law• Theories and Laws• Why Dinosaurs Disappeared• The Hellenic Market• Four-Element Theory• Drunken Goldfish• Science and Morality
Using the scientific method requires that one be a good observer.
observation inference
involves a judgmentor assumption
uses the fivesenses
The Skeptical Chemist
Robert Boyle
Published “The Sceptical Chymist”
…stated that scientific speculationscientific speculation was worthless unless it was supportedby experimental evidenceexperimental evidence.
This principle led to the development of the scientific methodscientific method.
(in 1661)
“My mother the eye doctor”
Observation or Inference?
One player is holding a bat.The player holding the bat is talking.One of the teams is called the “Reds.”One player is wearing a catcher’s mask.One player is a catcher.Names are written on the uniforms.The players in the picture are on opposite teams.The adult is the umpire.The piece of paper is a note from the mother of the batter.The adult is holding a piece of paper.The mother of the batter is an optometrist or opthalmologist (an eye doctor).
DataObservations are also called data.
There are two types of data.
qualitative data quantitative data
descriptions; measurements; no numbers must have numbers
Parts of the Scientific Method
• Identify an unknown.• Make a hypothesis
(a testable prediction).• Experiment to test
the hypothesis.• Draw a valid conclusion.
A Scientific Experiment
procedure
the order of events
in an experiment;
the “recipe”
Experiments must be controlled; they
must have two set-ups that must differ
by only one variable.
The conclusion must be based on the data.
variable
any factor that
could influence
the result
A Controlled Experiment?
Scientific Method
• Observations• Hypothesis• Experimentation
– Controlled (one variable changed at a time)– Collect data (quantitative and qualitative)– Analyze data (graph, statistics…trends)
• Form valid conclusion.
• After many experiments…form a theory.
Scientific Law vs. Scientific Theory
Law of Gravity
A theory tries to explain why
or how something happens.
A law states what happens.
Theory of Gravity
Atomic Theory
Collision Theory of Reactions
Theory vs. Natural Law
Scientific theory Natural law
Experiment
Hypothesis
analyze additional data
analyze initial observations
Make observationMake observation
Ask questionAsk question
Develophypothesis
Develophypothesis
Test hypothesis with an
experiment
Test hypothesis with an
experiment
Analyze dataand draw
conclusions
Analyze dataand draw
conclusions
Hypothesis IS
supported
Hypothesis IS
supported
Hypothesis is NOT
supported
Hypothesis is NOT
supported
Developtheory
Developtheory
Test hypothesis with furtherexperiments
Test hypothesis with furtherexperiments
Revisehypothesis
Revisehypothesis
Wysession, Frank, Yancopoulos, Physical Science Concepts in Action, 2004, page 8
Scientific Method
Results confirmed by other scientists –validate theorytheory.
Data do not supporthypothesishypothesis – revise or reject hypothesis
Stages In The Scientific Method
OBSERVING
•collecting data•measuring•experimenting•communicating
TESTING
•predicting•experimenting•communicating•collecting data•measuring
THEORIZING
•constructing models•predicting•communicating
PUBLISHRESULTS
•communicating
FORMULATINGHYPOTHESES
•organizing and analyzing data•classifying•inferring•predicting•communicating
Reviewing ConceptsWhat is Science?
• How does the scientific process start and end?
• How are science and technology related?• What are the branches of natural science?• Explain the advantages and disadvantages
of subdividing science into many different areas.
• Why do scientists seek to discover new laws of the universe?
Reviewing ConceptsUsing a Scientific Approach
• What is the goal of scientific methods?
• How does a scientific law differ from a scientific theory?
• What are scientific models useful?
• What are three types of variables in a controlled experiment?
• Does every scientific method begin with an observation? Explain.
Scientific Law
Laws of nature never change.
Charles’sLawV
1 V2T1 T
2
=
Theories and Laws
The Earth is flat…
Speeding kills (Audubon, Germany);
No explanation of why…but the theorytheory is if you drive at 120 mph and crash, an ambulance won’t need to be called (only next of kin).
seat belts save lives…LAWLAW: 65 mph and wear seat
belt
Why Dinosaurs Disappeared
Dinosaurs MeteorEarth Dust Cloud
Moon is formed
Ice Age - Glaciers
RIPMeteor Crater
Sun blocked
Evidence…
A theory…
The Original Metric Reference
H2O H2O= 1 meter = 1 kilogram = 1 liter
Length Mass Volume
1 kg
1/10 m
1/10 m
1/10 m
1/10,000,000
The Hellenic Market
Fire Water Earth Air
~~
Four Element Theory
• Plato was an atomist
• Thought all matter was composed of 4 elements:– Earth
– Water
– Fire
– Air
– Ether (close to heaven)
‘MATTER’
FIRE
EARTHAIR
WATER
Hot
WetCold
Dry
Relation of the four elements and the four qualities
Scientific Method and Law
Combustion & Phlogiston
• Phlogiston Theory• Combustion Theory• Burning Magnesium Metal in an Open Container• Burning Magnesium Metal in a Closed Container• Lighting a Bunsen Burner• Flame Temperature Distribution
Phlogiston Theory
(a) When an object burns
it gives off a substance
called phlogiston.
(b) When the space surrounding
the burning object is filled with
phlogiston, the object will no
longer be able to burn.
Phlogiston theory of burning
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 4
Combustion Theory
Modern theory of burning
(c) When an object burns, it uses
up a substance (oxygen) in
the surrounding space.
(d) When the space surrounding
the burning object has too little
oxygen in it, the object will no
longer be able to burn.
Antoine Lavoiser
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 4
Phlogiston Theory of Burning
1. Flammable materials contain phlogiston.
2. During burning, phlogiston is released
into the air.
3. Burning stops when…
…object is out of phlogiston, or
…the surrounding air contains
too much phlogiston.
Burning Magnesium Metal in an Open Container
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 77
Burning Magnesium Metal in a Closed Container
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 77