A crystal is a solid material with atoms and molecules that are arranged in a consistent repeating pattern, creating one of seven geometrical shapes. Crystals can be expensive and beautiful, like amethysts or diamonds, but they can also be found right in your kitchen in the form of sugar and salt! You can easily grow crystals by adding a crystal-forming chemical to water and waiting for the water to cool or evaporate.
Growing crystals can take several days, but this super-easy recipe gives you a cup full of needle-like crystals in just a few hours!
Epsom salt is another name for the chemical magnesium sulfate. The temperature of the water determines how much magnesium sulfate it can hold; it will dissolve more when it is hotter. Cooling the solution rapidly encourages fast crystal growth, since there is less room for the dissolved salt in the cooler, denser solution. As the solution cools, the magnesium sulfate atoms run into each other and join together in a crystal structure. Crystals grown this way will be small, thin, and numerous. To grow large single crystals, you'll need to follow the evaporation procedure in the next project.
Crystal Growing Experiment Kit
Grow crystals you can eat! This unique crystal kit uses pure sucrose and "seeded" crystal growing sticks to make large, beautiful rock candy crystals in just one week. The kit comes with one pound of pure sucrose for clear crystals. The rock candy can form in just seven days! You provide adult supervision, a saucepan, and water.
You can grow single, large crystals that look like gems by using a seed crystal. Here's how to do it:
The small crystals that formed in the saucer grew because of nucleation. A few alum molecules found each other in the solution and joined together in a crystal pattern. Other alum molecules continued to join them until enough molecules gathered to become a visible crystalline solid. (Chemists call that a crystal "falling out of" the solution.) If you left these crystals in the solution they would continue to grow, but they wouldn't get very big because they would all be competing for the remaining alum molecules in the solution. Instead, you took one crystal and used it as the only nucleation site in the solution. It was the primary site for the alum molecules to join together, so the crystal could grow quite large!
There are many factors that affect crystal growth, so crystal projects are great for scientific experimentation and science fairs. For example, many crystals are formed because of evaporation. Temperature and humidity are two things that affect the rate of evaporation, so you could design an experiment to see how different temperatures and humidity levels affect the rate of crystal growth and the size of crystals. Another aspect to test is the rate at which your solution is cooled: if you make a solution with boiling water, will crystals grow better if it's allowed to come to room temperature slowly or if it's cooled in the refrigerator?
There are many substances that can be used to grow crystals. You could design an experiment to test which one grows larger crystals under the same conditions. Try alum, Epsom salt, table salt, sugar, baking soda, or non-household chemicals like copper sulfate (blue crystals) and potassium ferricyanide (red crystals) - adult supervision is required for the last two.