Crystals
Alyce Sutton Miller Julia W. Howe Middle School
721 Lorel
Chicago IL 60644
(312)534-6060
Objectives:
This activity is designed for use with grades five through nine.
The students will:
1. answer questions concerning crystals;
2. realize that crystals are very prevalent;
3. see that crystals form naturally but realize that they can be
manufactured;
4. heat a solution and observe crystals forming;
5. observe formation of silver crystals;
6. realize that crystals have definite shapes;
7. observe crystal shapes and determine the best places to cleave for
smooth edges; and,
8. form definite crystal shapes.
Materials Needed:
samples of crystals overhead projector
hot packs (9) slides
1 L. Salol (liquid and "seed") vials with covers
1 L. Silver Nitrate copper wire (2" per student)
worksheets coarse salt crystals
a dish with glass beads 1 L. Sodium Acetate
single-edge razor blades (15) alcohol burners (5)
Strategy:
1. The teacher will initiate the discussion by asking these questions:
What is a crystal? What are some examples? Where are they found? Do they
have a shape or color? How long does it take for crystals to form?
2. Distribute hot packs that can be activated with a metal disk and show
crystals forming.
3. Place a small amount of Salol on a slide and heat it over a flame. Allow the
Salol to cool to room temperature before dropping a small seed crystal into
it. Using a projection microscope, students are able to watch crystals grow.
4. Each student will be given a vial containing Silver Nitrate. After placing
copper wire (with insulation removed) inside and replacing the cap, the
students will record their observations.
5. The students will be given handouts of the shapes which they are to form.
They are to count sides and identify shapes. Students will be told that
these are three-dimensional shapes.
6. A dish with glass beads will be placed on the overhead projector and tapped
lightly so that definite shapes form.
7. Using a single-edge razor blade and some Halite (coarse salt) crystals, the
students will cleave desired shapes.
8. Sodium Acetate will be heated until it becomes a liquid. A "seed" crystal
will be placed in a dish and the Sodium Acetate poured slowly but steadily
until a "mountain" forms.
Performance Assessment:
The teacher will observe the students to insure that they are completing the
experiments correctly; that they are able to define and give examples of
crystals; and that they are able to form and name at least two crystal shapes.
Conclusion:
The students will realize that all crystals have definite shapes and that they
form naturally in nature.
CRYSTAL SHAPES
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Cubic (regular) | |
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_____________
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Tetragonal | |
|_____________|_____________ _____________ _____________
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|_____________|_____________|_____________|____________|
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|_____________|
Orthorhombic __________
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|__________|________ ____________ ________
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|__________|________|____________|________|
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|__________|
Hexagonal
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|__________|/ \ |
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|__________|
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