grade 7 science...mixtures vs. pure substances mixtures... may have distinct visible components. may...
TRANSCRIPT
Grade 7 Science
Unit 3:
Mixtures & Solutions:
The Particle Theory
Particle Theory of Matter
All matter is made up of
tiny particles.
These particles are always
moving… they have
energy.
There are spaces among
particles.
There are attractive forces
between the particles.
The particles of one
substance differ from the
particles of other
substances.
Student Activity...
With a partner decide:
1. How would you tell the
difference between a pure
substance and a mixture?
2. How would use the
Particle Theory of Matter
to support your answer to
question #1?
Mixtures vs. Pure
Substances
Mixtures...
MAY have distinct visible
components.
MAY appear uniform
throughout.
They are the physical
combination of two or
more pure substances.
+
Sugar Water
= ?
Examples of Mixtures…
•salt water, kool-aid
•chocolate chip cookie
•muddy water
•salad dressing
•air
Pure Substances... ALWAYS appear as
uniform throughout
They contain either a
single atom or two or more
atoms chemically
combined to form a
different substance.
Examples of Pure Substances
•sugar (C12H22O11)
•gold (Au), copper (Cu)
•distilled water (H2O)
•carbon dioxide (CO2)
•oxygen (O2)
Student Activity...
Read pages 232, 236 and 237
Make a list of 15-20 solutions
and mixtures that you
encounter in a day. * those
that may pose a safety risk.
Grade 7 Science
Homogeneous &
Heterogeneous
Mixtures
Homogeneous Mixture
also called
solutions
can be
solid, liquid
or gas
Stainless steel
the particles
are evenly
mixed so
that none of
the original
substances
are visible Kool-aid
they appear
to be ONE
substance
light passes
through
unaffected
Heterogeneous Mixtures
also called
mechanical
mixtures
can be
solid, liquid
or gas Granola bar
the different
parts are visible
to the eye (may
need a
microscope)
the particles do
not evenly mix
Concrete
Light will
reflect
perpendicula
r to the
direction of
the beam
Student Activity...
Create a chart and list the
various homogeneous and
heterogeneous mixtures in
your home.
Share with your shoulder
partner and add to your
list.
The Tyndall Effect
A phenomenon that can be
used to distinguish between
solutions and what appears
to be a solution
cannot be used to distinguish
between a solution and a
pure liquid
In a Solution...
Light passes
unaffected (if a
student looks at the
beaker perpendicular
to the direction of the
beam they will NOT
see it
In a Mechanical Mixture...
The light will
scatter as it
passes through
the mixture
because all
particles are not
dissolved (as
Both Hetero and
Homogenoeus Mixtures?
Complete Activity 7-1C
Page 238 & 239
Post Activity Discussion...
Enrichment
Colloids
Dispersions
Emulsions