You have probably seen lots of crystals, but just what are they and how do they form? Grow some crystals of your own to find out more about these fascinating and beautiful wonders!
Get ready to watch some cool crystals grow and when you're done, you can eat them!
Optional: To make your rock candy more colorful, try adding 1-2 drops of food coloring to your sugar solution before putting the string in.
In step two you made a saturated solution -- there was so much sugar in the water that the water didn't have room to dissolve any more, so some was left in the bottom of the pan. When you dipped the string into the solution in step five, some of the dissolved sugar stuck to the string. Once the saturated solution started to cool, the loose sugar molecules in it (called the solute) started to join with the sugar molecules on the string. Then, the water molecules (called the solvent) started to evaporate or dry up into the air, leaving sugar molecules behind. Those molecules gradually joined with the sugar molecules on the string and became crystals. Because all of the solute molecules are the same (they are all sugar), they all form the same shape of crystals and they all stick together, making a big chunk of sugar crystals that are pretty to look at and tasty to eat!
Note that this is a special science project that is safe to eat because you only used food products, not any chemicals, and you used clean dishes from your kitchen. Never eat any experiment unless it is made entirely out of food and you only used clean dishes to prepare it.
In this project you can grow crystal snowflakes from a chemical called Borax and use them as pretty winter decorations!
Optional: To make colored snowflakes, use colored pipe cleaners and add 1-2 drops of food coloring in step four. To make your snowflakes glow in the dark, paint the pipe cleaner snowflake with glow-in-the-dark paint in step two and let it dry completely before going on to step three. Tie a ribbon to one point of your snowflake to make a Christmas tree ornament!
Just like in the rock candy project, you made a saturated solution of Borax, which is a chemical that forms crystals when the conditions are right. By mixing it with hot water and letting it cool and having something for the Borax (solute) molecules to attach to (the pipe cleaner snowflake), you gave the solution the right conditions to grow crystals! Once the crystals started to grow on your snowflake shape, more and more crystals formed around them. Ice crystals that real snowflakes are made of are not quite like these Borax crystals, but they do look sort of similar and they both are pretty and sparkle when light shines on them. Real ice crystals are made only of water. The difference is that they are formed when water vapor in clouds freezes and falls to the ground as snowflakes! Frost is another form of ice crystals that you might see on windows and grass on early, cold mornings. To learn more about snow and ice crystals, check out our Snow and Hail issue of this newsletter.
Salt vs. Sugar
How can you tell the difference between sugar and salt? They're both crystals and they look very similar - they are both white-colored, small grains. Of course if you tasted them both, you would know right away which one was salt and which was sugar because they taste very different. In this project you will find out how to tell sugar and salt apart just by looking at them!
Sugar and salt grains are actually tiny crystals. If you were to make a saturated solution of each of them, you would be able to see them grow into much larger crystals, but they would always have the same shape as these tiny crystals do! The salt crystals are cube shaped (like dice) and have six sides. The sugar crystals are very rough looking and are shaped more like rectangles with pointed ends. Most of the crystals are the same shape and size and look very similar to each other, but you probably saw a few crystals on your paper that looked a little different. Those crystals probably had pieces broken off of them, or there might even be more than one crystal stuck together, making them look different from the others. Also, the coloring of the crystals is a little different. Sugar crystals look very clear and sparkly while salt is duller and looks more white-colored or frosted.
Can you tell if the picture above is of salt or sugar? Highlight after this sentence for the answer: it's Sugar!
No matter how big a crystal gets, it will always grow in the same shape!
A diamond is the hardest crystal in the world.
A person who studies crystals is called a crystallographer.
What did the snowman and his wife put over their baby's crib? (Answer: A snow-mobile!)
What does a snowman like to eat for breakfast? (Answer: Frosted flakes!)
What is a rock's favorite cereal? (Answer: Coco-pebbles.)
Way Cool Websites
Learn more about the different shapes that crystals can have.
See pictures of the world's largest amethyst geode!
What Are Crystals?
A crystal is a hard, solid substance made of molecules that bond together in specific patterns to form an interesting shape that has straight edges and flat surfaces. Not all crystals have the same shape, as you saw in the salt vs. sugar project - there are actually lots of different kinds of crystals, and each kind has its own special shape. Some crystals that you are probably very familiar with are sugar, salt, and ice. But many other solids are made of crystals too; we just can't see them because they are so small! Lots of minerals form beautiful crystals that are used for jewelry, like diamonds or emeralds. Crystals are often transparent, which means that you can see through them sort of like you can see through glass. Other kinds have beautiful colors.
What Are They Made Of?
What a crystal is made of actually depends on what kind of crystal it is -- for example, salt, sugar, and snowflakes are actually formed out of different kinds of crystals! Snowflakes are made from crystals formed by frozen water. (You can see a picture here.) Salt crystals are formed by some chemical elements -- sodium and chlorine -- which join together in a crystal shape. (You can see a picture of salt crystals here.) Sugar crystals and rock crystals are made up of different chemical elements, too.
Crystals can be formed in several different ways. Most crystals are formed through evaporation. For example, when water from saltwater evaporates (or is dried up into the air), salt crystals are left behind (do the Borax Snowflakes project to see this happen). Ice crystals are formed when water from the Earth evaporates into the air and becomes a gas called water vapor. The water vapor becomes clouds and then freezes and falls back down to earth as snow. Ice crystals can also form as frost on windows and on the ground when the air has a lot of moisture (water vapor) and the temperature is below freezing. Some types of crystals are formed from melted rock in the earth (remember this from when we talked about Volcanoes?). When the hot rock cools gradually, it will sometimes form crystals. Geodes are round rocks that are formed when bubbles are trapped in the melted rock. As the bubbles cool down, crystals grow inside of the bubble of rock!
As a crystal grows, the pattern that makes it a certain shape will be repeated over and over, so the crystal will always keep the same shape as it gets bigger! The chemical elements that a crystal is made of are what tell the crystal what shape it will be. A crystal of salt is a different shape than a crystal of sugar (do the Salt vs. Sugar project to see for yourself!) because they are both formed from different elements. A lot of crystals might seem to look alike at first glance, but what elements the crystal is made out of will make it a unique shape and color. Even the same element can make different crystals, though, based on conditions such as temperature and light and what other elements are around. For example, the graphite used inside of pencils is a kind of crystal made from the element carbon, which is actually the same element that diamonds are formed from!
Ways Crystals Are Used
Use this worksheet along with the Salt vs. Sugar project to let kids draw their results from the project! The other half of the page will help them review which things are made f crystals and which are not.