Monday, Sept. 30th: “A” Day
Tuesday, Oct. 1st: “B” Day
Agenda
 Lab questions/problems - collect
 Section 2.2: “Studying Matter & Energy”
scientific method, hypothesis, variable, control,
theory, law, law of conservation of mass
 Scientific Method activity
 Serendipitous Discoveries Assignment/library work time
 Homework:
Sec 2.2 review, pg. 53: #1-7
Concept Review: “Studying Matter and Energy”
Lab: “Physical and Chemical Change”
Questions/Problems?
Make sure your conclusion questions are
answered fully in complete sentences…
Remember to write your
reflection statement!
The Scientific Method
Scientific Method: a series of steps followed
to solve problems, including collecting data,
formulating a hypothesis, testing the
hypothesis, and stating conclusions.
The scientific method is NOT a series
of exact steps, but rather a strategy
for drawing sound conclusions.
Experiments are Part of the Scientific
Method
An experiment is the process by which
scientific ideas are tested.
Scientists are often confronted by situations in
which their results don’t turn out as expected.
Scientists don’t view these results as failures.
Unexpected results often give scientists as
much information as expected results do.
Unexpected results are as important as
expected results.
Scientific Method Activity
Get in groups of 4.
Without opening the bags, use the scientific
method to see if you can correctly identify the
contents of each bag.
Be quiet so the other groups don’t hear you
and record your answers on a piece of paper.
How many processes that are part of the
scientific method did you use?
How many items did you identify correctly?
Scientific Discoveries Can Come From
Unexpected Observations
Some important discoveries and
developments have been made simply by
accident.
Teflon was
discovered by chance.
Scientific Discoveries Can Come From
Unexpected Observations
 Teflon is used as a thermal insulation device in
clothing, as a component in wall coverings, and
as a protective coating on metals, glass, and
plastics.
 Teflon’s properties of very low chemical reactivity
and very low friction make it valuable in the
construction of artificial joints for human limbs.
 Teflon is also used as a
roofing material.
Scientific Explanations
Hypothesis: a theory or explanation that is
based on observations and that can be tested.
Hypotheses are tested by carrying out
experiments.
Scientists Must Identify the Possible
Variables
Variable: a factor that could affect the results
of an experiment.
A scientist changes variables one at a time to
see which variable affects the outcome of an
experiment.
To know if your hypothesis is right, the
experiment must be designed so that each
variable is tested separately.
Each Variable Must be Tested
Individually
When a variable is kept constant from one
experiment to the next, the variable is called a
control and the procedure is called a
controlled experiment.
Data From Experiments Can Lead to a
Theory
Theory: an explanation for some
phenomenon that is based on observation,
experimentation, and reasoning.
Any hypothesis that withstands repeated
testing may become part of a theory.
Because theories are explanations, not facts,
they can be disproved but can never be
completely proven.
Theories and Laws Have Different
Purposes
 Law: a summary of many experimental results
and observations; a law tells how things work.
 While a theory is an attempt to explain the cause
of certain events in the natural world, a scientific
law describes the events.
 A law is a statement or a mathematical
expression that reliably describes the behavior of
the natural world.
Theories and Laws Have Different
Purposes
Law of conservation of mass: the law that
states that mass cannot be created or
destroyed in ordinary chemical and physical
changes.
Products of a chemical reaction
have the same mass as the
reactants have.
Models Can Illustrate the
Microscopic World of Chemistry
Model: a representation of an object, a
system, a process, or an idea.
A model is simpler than the actual thing that is
modeled.
Models can be most useful in understanding
what is happening at the microscopic level.
Serendipitous Discoveries Assignment
Your assignment is to research and write a 1
page paper about a serendipitous discovery.
The paper can be hand-written or typed, but
must be at least 1 full page in length.
You must use at least 2 sources and those
sources must be listed at the end of the paper.
You will have time today to begin your research.
The rest will be completed outside of class.
You will share your finding with the class on the
day the paper is due.
Homework
Sec 2.2 Review, pg. 53: #1-7
Work on serendipitous discoveries paper
Concept Review: “Studying Matter and Energy”
Due on day of Chapter 2 test (Oct. 17th/18th)
Next Time:
Section 2.2 quiz