Chapter 3 – Section 3
Compounds and Mixtures
Pages 87 - 91
Substances
• Matter that has the same composition and
properties throughout is called a substance.
• When different elements combine, other
substances are formed.
• Can you think of an example?
• Example: Hydrogen + Oxygen = Water (H2O)
Types of Matter
• Matter can be broken down into three
basic types:
1) Elements
2) Compounds
3) Mixtures
Compounds
• A compound is a substance made of two
or more elements that are chemically
combined in a specific ratio.
• Compounds are often very different from
the elements that make them up.
• For example…….
Compound Properties
Sodium Na
Chlorine Cl
A soft metal that will REACT
vigorously with water.
A yellow-green dense gas that
is extremely poisonous!
Compound Properties
• Sodium + Chlorine = Sodium Chloride
Na
+
Cl
=
NaCl
OR
Compounds Have Formulas
• A formula is a combination of symbols that
shows the ratio of elements in a compound.
• EXAMPLE:
Water: H2O
2 atoms of hydrogen and 1 atom of Oxygen
Try to complete the following examples on your
own:
Carbon Dioxide, Hydrogen Peroxide, Salt
Compound Formulas
• Carbon Dioxide (CO2)
• 1 atom of Carbon and 2 atoms of Oxygen
• Hydrogen Peroxide (H2O2)
• 2 atoms of Hydrogen and 2 atoms of Oxygen
• Salt (NaCl)
• 1 atom of Sodium and 1 atom of Chlorine
One Atom Makes a Big Difference
• Water (H2O)
• Non-irritating liquid used for bathing & drinking.
• Add another atom of Oxygen and….
• Hydrogen Peroxide (H2O2)
• Not safe if it gets in your eyes (irritating)
Mixtures
• A mixture is when two or more substances
(elements or compounds) combine but do
not form a new substance.
• For example…..
• Salt Water = Salt + Water
• Air = Nitrogen + Oxygen + Other gases
Compounds vs. Mixtures
•
•
•
•
Compounds
Substances in
compounds lose their
individual properties.
Parts do have specific
“ratios”
Parts are chemically
combined
Parts cannot be
separated by physical
means, only
chemically.
•
•
•
•
Mixtures
Substances in mixtures
keep their individual
properties.
Parts DO NOT have
specific ratios
Parts are physically
combined
Parts can be separated
physically and are just
‘mixed’ together.
Two Types of Mixtures
• Homogeneous
– Cannot see individual
particles
– Well mixed
– Mixture looks the
same throughout
• Heterogeneous
– Can see individual
particles
– Not well mixed
– Mixture does not look
the same throughout.
Solutions
• Another name for a homogeneous mixture is a
solution.
• The substance that dissolves or seems to
disappear is the solute.
• The substance that dissolves the solute is called
the solvent.
•
•
•
•
Example: Chocolate Milk
Solute = Chocolate
Solvent = Milk
Solution = Chocolate Milk