A crystal is a solid that consists of the various atoms, ions, or molecules being arranged in a uniform repeating pattern. This results in the material having a specific shape and colour, and having other characteristic properties. Diamond (used in jewelery, and cutting tools) is an example of a crystal; it is made of pure carbon. Graphite (used in pencils and lubricants) is also a crystal made from carbon. Salt and sugar are also examples of crystals.
Recrystallization is a process that has been used to purify solid material by dissolving the solid (called a solute) in an appropriate liquid (called a solvent) and then having the material come out of solution in crystalline form. Depending upon conditions, one may obtain a mass of many small crystals or one large crystal.
More detailed information can be found on
shapes & sizes,
light and colour
and, how crystals form.
Here are answers to some
frequently asked questions about crystals.
National Chemistry Week is an initiative of
The Chemical Institute of Canada that strives to publicize the benefits of this science to our society. It is usually held the first full week after Thanksgiving.
One of the national initiatives is the Crystal Growing Contest among high school students. This is intended to be a fun, hands-on experience, with the excitement of competition. Schools are provided with materials and/or instructions on what substance to use and how to grow crystals. The object is to grow the biggest and highest quality crystal possible. Each crystal is scored by a formula taking into account both size and quality. Prizes are awarded to the winning students both at the local and national levels.
Because all substances have the potential to be hazardous, we try to use those substances that are relatively easy to crystallize and are relatively non-hazardous. For the first few years of the contest we alternated between cupric sulfate pentahydrate ("bluestone") and aluminum potassium sulfate ("alum", used in water purification). The past two years we have used potassium sodium tartrate ("Rochelle salt"), which must first be made by reacting substances found in grocery stores.
The steps involve
To get to the next steps go to any of the following links:
General Introduction to Growing Crystals
Preparation of Seed Crystals
Growing Single Crystals
Growing Single Crystals in the Presence of Introduced "Contaminants"
Preparation of Rochelle Salt
How We Judge the Crystals
View Examples of Previously Submitted Crystals
Although not part of our competition, there are lots of fun preparations of multiple crystals. These include growing:
Crystals of Sugar sometimes called "Rock Candy",
Crystals on a String using baking soda, procedures by Kiwi.
Crystal Gardens, procedures by Kiwi.