TOPIC: Crystal Formation
To demonstrate how crystals form
Graduated cylinder, beaker or cup and measuring spoon, Epsom salts, scissors, black construction paper, petri dish
Cut a piece of black paper to fit inside the petri dish. Fill the graduated cylinder or beaker with 250 ml of water (1 cup). Add 60 ml (1 tablespoon) of Epsom salts to the water and stir. Pour a thin layer of the mixture into the petri dish. The petri dish should stand undisturbed for one day. Try repeating this experiment using different amounts of Epsom salts. Can you think of other ways to vary this experiment.
What shape are the crystals that form on the paper? Record your results and make a sketch of your observations and label.
As the water slowly evaporates from the solution the Epsom salts molecules move closer together . The salt molecules line up in an orderly pattern to form long needle shaped crystals. The salt molecules stack together just like building blocks, and the shape of the crystal is ultimately determined by the shape of the molecules.
Adapted from experiment in Earth Science for Every Kid by Janice VanCleave
TOPIC: Bubble Crystals
To demonstrate how atoms arrange themselves in crystals
Dish detergent, shallow dish, straw, plastic ruler
Add detergent to water in a shallow dish or pan. Blow enough bubbles to cover the surface. Use the straightedge to move rows of bubbles past each other. Try changing the size of the straw to create different sizes of bubbles. Think of other ways to vary this experiment?
What kind of arrangements do the bubbles form? How do the different sizes of bubbles affect the experiment. How easy is it to separate the bubbles? Record your findings, make a sketch of your observations and label.
The different sized bubbles represent the different metals in crystalline alloys. Different size bubbles form a stronger bond and are more difficult to slide past each other than bubbles of the same size. Alloys have stronger bonds than pure metals.
Adapted from experiment in Rocks & Fossils by Ray Oliver