Introduction to chemistry. What is the scope of chemistry. Practical application of chemistry.

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Chapter 1
Introduction to Chemistry
1.1 The Scope of Chemistry
1.2 Chemistry and You
1.3 Thinking Like a Scientist
1.4 Problem Solving in Chemistry

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In 1928, Alexander
Fleming, a Scottish
scientist, noticed that the
bacteria he was studying
did not grow in the
presence of a yellow-
green mold.
CHEMISTRY & YOU
How do you think Alexander Fleming
tested his hypothesis?

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An Experimental Approach to Science
How did Lavoisier help to
transform chemistry?
An Experimental
Approach to Science

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The word chemistry comes from the word
alchemy.
• Alchemists were concerned with searching for a way to
change other metals, such as
lead, into gold.
• Alchemists developed the
tools and techniques for
working with chemicals.
• They designed equipment
that is still in use today,
including beakers, flasks, tongs,
funnels, and the mortar and pestle.
An Experimental
Approach to Science

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An Experimental
Approach to Science
In France, Antoine-Laurent Lavoisier did work in
the late 1700s that would revolutionize the
science of chemistry.

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An Experimental
Approach to Science
Lavoisier helped to transform
chemistry from a science of
observation to the science of
measurement that it is today.
In France, Antoine-Laurent Lavoisier did work in
the late 1700s that would revolutionize the
science of chemistry.

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An Experimental
Approach to Science
• Lavoisier designed a balance that could
measure mass to the nearest 0.0005 gram.
• He also settled a long-standing debate about
how materials burn.
– He was able to show that oxygen is required
for a material to burn.

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Who is credited with transforming
chemistry from a science of observation
to a science of measurement?
A. Fleming
B. Lavoisier
C. de Mestral
D. Carothers

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Who is credited with transforming
chemistry from a science of observation
to a science of measurement?
A. Fleming
B. Lavoisier
C. de Mestral
D. Carothers

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The Scientific Method
The Scientific Method
What are the steps in the
scientific method?

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The Scientific Method
The scientific method is a logical,
systematic approach to the solution of a
scientific problem.

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The Scientific Method
Steps in the scientific method
include making observations,
proposing and testing hypotheses,
and developing theories.

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The Scientific Method
Making Observations
When you use your senses
to obtain information, you
make an observation.
• This scientist is making
observations with a
microscope.
• Observation is an
essential step in the
scientific method.

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The Scientific Method
Making Observations
Suppose you try to turn on a flashlight
and you notice that it does not light.

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The Scientific Method
Testing Hypotheses
• A hypothesis is a proposed explanation
for an observation.
If you guess that the batteries in a
flashlight are dead, you are making a
hypothesis.

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The Scientific Method
Replacing the batteries is an experiment,
a procedure that is used to test a
hypothesis.
Testing Hypotheses

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The Scientific Method
Replacing the batteries is an experiment,
a procedure that is used to test a
hypothesis.
• The variable that you change during an
experiment is the independent variable,
also called the manipulated variable.
• The variable that is observed during the
experiment is the dependent variable,
also called the responding variable.
Testing Hypotheses

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The Scientific Method
For the results of an experiment to be
accepted, the experiment must produce
the same result no matter how many
times it is repeated, or by whom.
• This is why scientists are expected to publish
a description of their procedures along with
their results.
Testing Hypotheses

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The Scientific Method
Sometimes the experiment a scientist
must perform to test a hypothesis is
difficult or impossible.
• For example, atoms and molecules, which
are some of the smallest units of matter,
cannot be easily seen.
• A model is a representation of an object or
event.
• Chemists may use models to study chemical
reactions and processes.
Testing Hypotheses

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The Scientific Method
Developing Theories
Once a hypothesis meets the test of
repeated experimentation, it may be
raised to a higher level of ideas. It may
become a theory.
• A theory is a well-tested explanation for a
broad set of observations.

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The Scientific Method
Developing Theories
• When scientists say that a theory can
never be proved, they are not saying that
a theory is unreliable.
• They are simply leaving open the
possibility that a theory may need to be
changed at some point in the future to
explain new observations or experimental
results.

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The figure below shows how scientific
experiments can lead to laws as well as
theories.
The Scientific Method
Scientific Laws
Experiments
An experiment can
lead to observations
that support or
disprove a hypothesis.
Theory
A theory is tested by
more experiments
and modified if
necessary.
Hypothesis
A hypothesis may be
revised based on
experimental data.
Observations
Scientific Law
A scientific law
summarizes the results
of many observations
and experiments.

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The Scientific Method
A scientific law is a concise statement
that summarizes the results of many
observations and experiments.
Scientific Laws

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The Scientific Method
A scientific law is a concise statement
that summarizes the results of many
observations and experiments.
• A law doesn’t try to explain the
relationship it describes.
• That explanation requires a theory.
Scientific Laws

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CHEMISTRY & YOU
What was Alexander Fleming’s
hypothesis? How could he test his
hypothesis?

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Other scientists had made the
same observation, but
Fleming was the first to
recognize its importance. He
assumed that the mold had
released a chemical that
prevented the growth of the
bacteria.
CHEMISTRY & YOU
What was Alexander Fleming’s
hypothesis? How could he test his
hypothesis?

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What is a hypothesis?
A. information obtained from an experiment
B. a proposed explanation for observations
C. a concise statement that summarizes the
results of many experiments
D. a thoroughly tested model

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What is a hypothesis?
A. information obtained from an experiment
B. a proposed explanation for observations
C. a concise statement that summarizes the
results of many experiments
D. a thoroughly tested model

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Collaboration and Communication
What role do collaboration and
communication play in science?
Collaboration and
Communication

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• No matter how talented the players on a team
may be, one player cannot ensure victory for
the team.
• Individuals must collaborate, or work
together, for the good of the team.
Collaboration and
Communication

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When scientists collaborate and
communicate with one another,
they increase the likelihood of a
successful outcome.
Collaboration and
Communication

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Collaboration
Scientists choose to collaborate for
different reasons.
• Some research problems are so complex
that no one person could have all the
knowledge, skills, and resources to solve
the problem.
Collaboration and
Communication

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Collaboration isn’t always a smooth
process.
• Working in pairs
or in a group
can be
challenging, but
it can also be
rewarding.
Collaboration and
Communication
Collaboration

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Communication
The way scientists communicate with
each other and with the public has
changed over the centuries.
• Scientists working as a team can communicate
face to face.
• They also can exchange ideas by e-mail, by
phone, and at local and international
conferences.
• They publish their results in scientific journals.
Collaboration and
Communication

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Scientific journals are the most reliable source
of information about new discoveries.
• Articles are published only after being
reviewed by experts in the author’s field.
• Reviewers may find errors in experimental
design or challenge the author’s conclusions.
• This review process is good for science
because work that is not well founded is
usually not published.
Communication
Collaboration and
Communication

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Why are articles in scientific journals the
most reliable source of information about
new scientific discoveries?
A. The articles are reviewed by experts in the
author’s field.
B. Any article that is submitted is published.
C. Everyone has access to the information.
D. The articles are short and easy to read.

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Why are articles in scientific journals the
most reliable source of information about
new scientific discoveries?
A. The articles are reviewed by experts in the
author’s field.
B. Any article that is submitted is published.
C. Everyone has access to the information.
D. The articles are short and easy to read.

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Key Concepts
Lavoisier helped to transform chemistry
from a science of observation to the
science of measurement that it is today.
Steps in the scientific method include
making observations, testing
hypotheses, and developing theories.
When scientists collaborate and
communicate with one another, they
increase the likelihood of a successful
outcome.

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Glossary Terms
• scientific method: a logical, systematic approach to the
solution of a scientific problem; steps in the scientific
method include making observations, testing
hypotheses, and developing theories
• observation: information obtained through the senses;
observation in science often involves a measurement
• hypothesis: a proposed explanation for an observation
• experiment: a repeatable procedure that is used to test
a hypothesis

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Glossary Terms
• independent variable: the variable that is changed
during an experiment; also called manipulated variable
• dependent variable: the variable that is observed
during an experiment; also called responding variable
• model: a representation of an event or object
• theory: a well-tested explanation for a broad set of
observations
• scientific law: a concise statement that summarizes the
results of many observations and experiments

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Chemists use the scientific method to
solve problems and develop theories
about the natural world.
BIG IDEA

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