MAKING CRYSTALS

Everything around you is made up of tiny particles called atoms. Crystals consist of atoms that are arranged in a regular repeating pattern. This gives the Crystal its fixed outer shape. Most solid substances, including metals and minerals found in rocks, are in crystal form.

Igneous rocks are usually made of crystals that form as hot magma (molten rock) cools and solidifies. Crystal may also grow when a water solution containing minerals on the surface of the Earth evaporates. These two ways are demonstrated in the first two experiments.

The type of crystal that form depend on the substances that are dissolved in the liquid. Each mineral forms crystals with a characteristic shape. You can compare the crystals from the first two projects, which use two different solutions. The final experiment demonstrates how atoms are arranged in a crystal. In a liquid, the atoms are loosely joined together and can move around, which is why a liquid flows. As a liquid solidifies, the atoms join together in a regular pattern, like a pyramid, to form a crystal. When atoms are arranged in a disorderly way, they produce a gas.

GROWING CRYSTALS FROM SUGAR SOLUTION

Water, measuring cup, pan, sugar, tablespoon, wooden spoon, glass jar.

STEP 1
Ask an adult to heat a pint of water in a pan until it is hot, but not boiling. Using a tablespoon, add sugar to the hot water until no more sugar will dissolve in the solution.

STEP 2
Stir the solution well, then allow it to cool. When it is completely cold, pour the solution from the pan into a glass jar, and put it somewhere where it will not be disturbed.

After a few days or weeks, the solution starts to evaporate and the sugar in the solution will gradually begin to form crystals. The longer it is undisturbed, the larger your crystals will grow.

CRYSTALS FROM SODIUM CARBONATE

Carbonate, spoon, bowl, straw, cotton thread, paper clip, magnifying glass.

STEP 1
Get an adult to pour about 1 cup of very hot water into a pitcher. Add a spoonful of sodium carbonate. Stir until it all dissolves. Add more sodium carbonate until no more will dissolve.

STEP 2
Dissolving a solid in a liquid makes a solution. Your solution is said to be saturated, because no more solid will dissolve. Pour the solution into a bowl. Leaving undissolved solids in the pitcher.

STEP 3
A crystal needs somewhere to start growing. Use a piece of thread to attach the paper clip to the straw. The distance from straw to clip should be about two-thirds the depth of the bowl.

STEP 4
Balance the straw on top of the bowl to let the paper clip dangle in the water. As time goes by, water evaporates, leaving crystals on the paper clip.

STEP 5
After several days, remove the clip and crystals from the solution, and wash them under the cold tap. Look at the crystals through a magnifying glass. The shapes of your crystals are identical.

MAKE A MODEL CRYSTAL

Small, shallow tray (such as the lid of a shoebox), marbles of five different colors.

STEP 1
Fit a layer of blue marbles into the tray in a square pattern. Each central atom is surrounded by eight others. (In some substances, atoms are arranged in a hexagon – a six-sided shape.)

STEP 2
Add a second layer. Each marble sits in a clip between four marbles in the layer below. Add a third layer. Each marble is directly above a marble in the first layer.

STEP 3
Add two more layers of marbles to make up a complete model crystal. The model crystal you have made is the shape of a square pyramid, because you used a square tray.