CHAPTER 1
WHAT IS A CHEMICAL?
• A chemical is any substance that has a definite
composition.
• Chemical changes and reactions take place all the
time.
• Examples of chemical reactions:
• Photosynthesis –turns CO2 and sunlight into food
and oxygen
• Rusting of metal
• Burning a match
OBJECTIVES
• Distinguish between elements and compounds
• Distinguish between pure substances and mixtures
• Classify mixtures as homogeneous or
heterogeneous
• Explain the difference between mixtures and
compounds
CLASSIFYING MATTER
• Everything around you is made up of ___________.
• All matter is composed of ___________.
PURE SUBSTANCES
• Every pure substance has characteristic __________
that can be used to identify it.
• These properties can be ____________ or chemical.
• There are two types of pure substances,
____________ and ____________.
ELEMENTS
• Elements are pure substances that contain only one
kind of atom.
• Copper and bromine are elements.
• The __________ __________ is an organized list of all
the elements.
MOLECULES
• A ____________ usually consists of two or more atoms
combined in a definite ratio.
• Examples
• H2
• F2
• Cl2
COMPOUNDS
• Pure substances that are not ____________ are
compounds.
• Compounds are composed of more than one kind
of atom.
CLASSIFY THE FOLLOWING AS A PURE
SUBSTANCE, COMPOUND, OR
ELEMENT. CHOOSE ALL THAT APPLY
•
•
•
•
•
•
•
•
CO2
F2
C6H12O6
SO4
C 9 H 8 O4
H 2O
Fe
Ag
MIXTURES
• A mixture is a sample of matter that contains two or
more pure substances ___________ combined.
• Most kinds of foods are mixtures except _________
and _________.
• Air is a mixture
• Water (is, is not) a mixture
CLASSIFYING MIXTURES
• In homogeneous mixtures the pure substances that
are combined are distributed uniformly throughout
the entire mixture.
• Gasoline
• Syrup
• Air
• There different components cannot be seen
CONTINUED…
• In heterogeneous mixtures, the substances are not
evenly mixed
•
•
•
•
Italian dressing
Chocolate chip cookies
Salad
Muddy water
REVIEW
• What is the difference between an element and a
compound?
• What’s the difference between pure substances
and mixtures?
• What’s the difference between mixtures and
compounds?