CHEMISTRY
Compounds and Mixtures
SUBSTANCES
• A SUBSTANCE is matter that has the same
composition and properties throughout
*EXAMPLE—elements are substances
COMPOUND
•A substance whose smallest
unit is made up of atoms of
more than one element
bonded together is a
COMPOUND
•Compounds have
properties that are different
from the elements that
make them up
*EXAMPLE—Elements
hydrogen & oxygen are
colorless gases, but these
two elements can combine
to form the compound
water which is a
nonirritating liquid
COMPOUND (continued)
• Elements hydrogen & oxygen can also
combine to form another substance called
hydrogen peroxide
• What is hydrogen peroxide used for?
• Water (H₂O) and hydrogen peroxide (H₂O₂)
have different properties from the elements
that make it up and they also have different
properties from each other
COMPOUNDS
HAVE FORMULAS
•The chemical formula of a
compound tells you which
elements make it up as well
as how many atoms of each
element are present
•The subscript number
written below and to the
RIGHT of each element’s
symbol tells you how many
atoms of that element exist
in one unit of that
compound
•The coefficient number
written to the LEFT of each
compound tells you how
many molecules of each
compound there are
TIME TO TALK
•Talk to the people at
your table about what
a compound is and
give some real world
examples of
compounds.
MIXTURE
•When two or more
substances (elements or
compounds) come together
but don’t combine to make a
new substance, a MIXTURE is
formed
*EXAMPLE—blood, sugar &
water, sand & water
•The proportions of a mixture
can be changed without
changing the identity of the
mixture
*EXAMPLE—If you add
more sand or more water to a
sand & water mixture it’s still
sand & water
MIXTURE (continued)
• Mixtures can be separated in different ways (use
water, filters)
• Types of mixtures:
1. HOMOGENEOUS—the same throughout; you
can’t see the different parts (smoke, Kool Aid)
2. HETEROGENEOUS—has larger parts that are
different from each other; you can see the
different parts (vegetable soup, toy box full of
toys
TIME TO TALK
•With the people
at your table, talk
about how the
proportions of a
mixture relate to
its identity.
ASSIGNMENT
•You will read the
poem “Elements,
Compounds and
Mixtures” and answer
the questions that go
along with the poem.
•This is an INDIVIDUAL
assignment, therefore
there should be no
talking.
SUMMARY
• Answer the following on a half sheet of paper:
Compare and contrast compounds and
mixtures.