Chemical
Reactions
Chemical reactions form
new substances by
breaking and making
chemical bonds.
Key Concepts
SECTION
1
Chemical reactions
alter arrangements
of atoms.
Learn how chemical reactions
are identified and controlled.
SECTION
2
The masses of reactants
and products are equal.
Learn how chemical equations
show the conservation of mass.
SECTION
3
Chemical reactions
involve energy changes.
Learn how energy is
absorbed or released by
chemical reactions.
SECTION
4
Life and industry
depend on chemical
reactions.
Learn about some chemical
reactions in everyday life.
Prepare and practice for
the FCAT
• Section Reviews, pp. 294,
302, 309, 317
• Chapter Review, pp. 318–320
• FCAT Practice, p. 321
CLASSZONE.COM
• Florida Review: Content
Review and FCAT Practice
284 Unit 2: Chemical Interactions
What changes are
happening in this
chemical reaction?
Changing Steel Wool
Place a small lump of steel wool in a cup.
Pour in enough vinegar to cover the steel
wool. After five minutes, take the steel
wool out of the vinegar. Shake the steel
wool to remove any excess vinegar.
Place the steel wool in a small plastic
bottle, and cover the mouth of the
bottle with a balloon. Observe the
steel wool and balloon after one hour.
Observe and Think What happened
to the steel wool and balloon? What
might have caused this to occur?
A Different Rate
Half fill one cup with hot tap
water and a second cup with
cold tap water. Drop a seltzer
tablet into each cup at the
same time. Time how long
it takes for each tablet to
stop fizzing.
Observe and Think
Which tablet fizzed for a
longer period of time? How
might you explain any differences?
Internet Activity: Reactions
Go to ClassZone.com to explore chemical
reactions and chemical
equations. Learn how a
chemical equation can be
balanced.
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Observe and Think How
do chemical equations
show what happens during
a chemical reaction?
NSTA
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Chemical Reactions Code: MDL024
Chapter 9: Chemical Reactions 285
CHAPTER 9
CONCEPT REVIEW
VOCABULARY REVIEW
• Atoms combine to form
compounds.
electron p. 225
• Atoms gain or lose electrons
when they form ionic bonds.
covalent bond p. 264
• Atoms share electrons in
covalent bonds.
atom, chemical change
ionic bond p. 262
See Glossary for definitions.
FLORIDA REVIEW
CLASSZONE.COM
Content Review and FCAT Practice
TAKING NOTES
COMBINATION NOTES
To take notes about a
new concept, first make
an informal outline of the
information. Then make
a sketch of the concept
and label it so you can
study it later.
NOTES
Chemical reactions
• cause chemical changes
• make new substances
• change reactants
into products
VOCABULARY
STRATEGY
Write each new vocabulary
term in the center of a
four square diagram.
Write notes in the squares
around each term.
Include a definition, some
characteristics, and some
examples of the term.
If possible, write some
things that are not
examples of the term.
286 Unit 2: Chemical Interactions
Evidence of Chemical Reactions
before
after
increase in temperature
Definition
substance present
before a chemical
reaction occurs
Characteristics
its bonds are
broken during
a reaction
REACTANT
Examples
Nonexample
oxygen in a comcarbon dioxide in a
bustion reaction
combustion reaction