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CHEM 1211 - Principles of Chemistry I
Chapter 1 - Chemical Foundations
Chemistry is the study of matter and the changes it undergoes.
1.1 Chemistry: An Overview
!two fundamental concepts of chemistry:
"(1) matter is composed of various types atoms, and
"(2) one substance changes to another by reorganizing the way the atoms are attached to
each other
!with an electric current the following reaction can occur
222
HO ÷ H + O
"with a spark the following reaction can occur
22 2
H + O ÷ HO
Science: Process for Understanding Nature and Its Changes
Scientists use the scientific method:
!(1) Making observations (collecting data)
!(2) Making a prediction (formulating a hypothesis)
!(3) Do experiments to test the prediction (testing the hypothesis).
1.2 The Scientific Method
!see Fig. 1.4
!one a set of hypotheses that agrees with the various observation is obtained the hypotheses
are assembled into a theory
!a theory, which is often called a model, is a set of tested hypotheses that gives an overall
explanation of some natural
!important to distinguish between observations (things that can be witnessed and recorded)
and theory (interpretation - a possible explanation of why nature behaves in a particular way)
!remember that theories (models) are human inventions; they attempt to explain observed
natural behavior in terms of human experiences
!as scientists observe nature, they often see that the same observations applies to many
different systems, e.g.,studies of innumerable chemical changes have shown that the total
observed mass of the materials involved is the same before and after the change; such
generally observed behavior is formulated into a statement called a natural law; the
observation that the total mass of materials is not affected by a chemical change in those
