1.2 Scientific Method
Thinking Like a Scientist
Linus Pauling won
the Nobel Prize in
Chemistry in 1954.
Learning Goal Describe the activities that are part of the
scientific method.
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Twelfth Edition
© 2015 Pearson Education, Inc.
The Scientific Method
The scientific method is a set of general principles that helps
to describe how a scientist thinks.
1. Make observations about nature and ask questions about
what you observe.
2. Propose a hypothesis, which states a possible explanation of
the observations.
3. Several experiments may be done to test the hypothesis.
4. When results of the experiments are analyzed, a conclusion
is made as to whether the hypothesis may be true or false.
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Twelfth Edition
© 2015 Pearson Education, Inc.
Using the Scientific Method
Suppose you visit a friend in her home, and soon after you
arrive, you begin to sneeze.
• You observe that your friend has a new cat.
• You ask yourself why you are sneezing and form a hypothesis
that you are allergic to cats.
• You perform experiments to test your hypothesis by visiting
other friends with cats.
• If you sneeze after leaving the other homes with cats, you
come to the conclusion that your hypothesis is correct.
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Twelfth Edition
© 2015 Pearson Education, Inc.
Using the Scientific Method
Through your observations, you may determine that you
are allergic to cat hair and dander.
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Twelfth Edition
© 2015 Pearson Education, Inc.
Using the Scientific Method
The hypothesis is
modified if the
results of the
experiments do
not support it.
The scientific method develops conclusions using observations,
hypotheses, and experiments.
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Twelfth Edition
© 2015 Pearson Education, Inc.
Study Check
Identify each of the following as an observation (O), a
hypothesis (H), an experiment (E), or a conclusion (C):
A. During your visit to the gym, your trainer records that you
ran for 25 minutes on the treadmill.
B. Scientific studies show that exercising lowers blood
pressure.
C. Your doctor thinks that your weight loss is due to increased
exercise.
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Twelfth Edition
© 2015 Pearson Education, Inc.
Solution
Identify each of the following as an observation (O), a
hypothesis (H), an experiment (E), or a conclusion (C):
A. During your visit to the gym, your trainer records that you
ran for 25 minutes on the treadmill. Observation (O)
B. Scientific studies show that exercising lowers blood
pressure. Conclusion (C)
C. Your doctor thinks that your weight loss is due to increased
exercise. Hypothesis (H)
Chemistry: An Introduction to General, Organic, and Biological Chemistry, Twelfth Edition
© 2015 Pearson Education, Inc.