A Crop of Crystals

Computer chips, diamonds, rubies, quartz rocks, salt; all of these are crystals. This time of the year you may have decorations with crystals or imitation crystals (usually glass) all around. When the atoms or molecules of a substance line up in a regular order, a crystal is formed. The shape of the crystal will depend on what chemical it is.

Computer chips are made on slices of a crystal of silicon, an element found in sand. Diamonds and rubies and other gems are also crystals. Even the salt on your table is a crystal.

Crystals are usually formed by dissolving the substance in a solution and then letting the liquid evaporate. Would you like to make your own crop of crystals?

You will need:

two small plates black construction paper table salt Epsom salt water tablespoon dropper or small spoon magnifying glass

How to do it:

1. Cover two small plates with black construction paper.

2. Fill two small jars about half full of warm water.

3. Measure two tablespoons of table salt and put in one jar. Put the lid on and shake for thirty seconds. The mixture may still look cloudy. Using the dropper or a small spoon, put a small pool of the liquid on the paper in the saucer. Try not to get any undissolved salt in the dropper.

4. Measure two tablespoons of Epsom salt and put in the other jar. Put the lid on and shake. Put a small pool of the liquid on the paper.

5. Put the two saucers in a place where they will not be bumped or touched. Check them after a day, after two days. What do you see? Look with the magnifying glass.

What happens:

As the water evaporates, crystals appear. The table salt crystals are cube-shaped, while the Epsom salt makes long needle-like crystals. Table salt is sodium chloride, NaCl, one atom of sodium and one atom of chlorine. These atoms crystallize in a cubic shape.

Epsom salt is magnesium sulfate, MgSO4. When this chemical crystallizes, the atoms arrange themselves so that the crystal is a long slender needles.

There are many other chemicals that will grow as crystals. You might find a library book that will tell you how to build a crystal garden with different shapes of crystals.

If you would like to see some crystal images, check out these web sites.

http://www.bsu.edu/teachers/academy/gems...

http://www.intel.com/education/chips/ind...

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