Notes from Tuesday, 10/26/10

1. Compounds
Chapter 5, Section 2
10/26/10

2. Section 2 Compounds
Chapter 5
Compounds: Made of Elements
• A compound is a pure substance
composed of two or more elements that
are chemically combined.
• Elements combine by reacting, or
undergoing a chemical change, with
one another.
• A chemical reaction is the process by
which substances change into new
substances.

3. Section 2 Compounds
Chapter 5
Compounds: Made of Elements
• During a chemical reaction, the atoms of two
or more elements react with each other to
form molecules of compounds.
• When two or more elements combine, a new
compound is formed. The properties of the
new compound are different from the
properties of the elements that formed the
compound.

4. Compounds: Made of Elements,
continued

5. Section 2 Compounds
Chapter 5
Properties of Compounds
• Each compound has unique physical
and chemical properties.
• A compound has properties that differ
from the properties of the elements that
make up the compound.
• Elements always join in a specific ratio
to form a specific compound.

6. Section 2 Compounds
Chapter 5
Breaking Down Compounds
• The only way to break down a
compound is through a chemical
change.
• Some compounds can be broken down
into their elements.
• Other compounds can be broken down
to form simpler compounds.

7. Section 2 Compounds
Chapter 5
Compounds in Your World
• The compounds found in nature are not
usually the raw materials needed by
industry. Often, these compounds must
be broken down to provide elements or
other compounds that can be used as
raw materials.
• Proteins and carbon dioxide are two
compounds that play an important role
in living things.