Crystals
What is a crystal? A crystal is a solid substance with definite geometric shapes and molecules that are arranged in a repeating pattern (Comptonıs ). Crystals have fixed angles between its faces, which have distinct edges. If the faces of a crystal can reflect light, then it will sparkle (Stangle). Crystals have constant angles because of the regular arrangement of its particles. There are seven types of crystals: cubic, tetragonal, orthorhombic, hexagonal, trigonal, monoclinic, and triclinic (Dr. Boyle). Crystals are classified by the shapes of their lattice or the ³regular, periodic configuration of particles² (American Heritage). There are two different types of lattices. There are primitive lattices where there is only one lattice point per unit cell. There are also non-primitive lattices. They are the ones with more than one lattice point per unit cell. Crystals can also be classified by their physical/chemical properties. There are four types of crystals classified this way. They are covalent, metallic, ionic, and molecular (Dr. Boyle). A covalent crystal is a crystal which is one big molecule. They usually have extremely high melting points. An example of a covalent crystal is a diamond an
The scientific definition of a crystal is based on its internal structure rather than its outward appearance. In order for a substance to be a crystal its molecules must be arranged in a repeating pattern. A single crystal grows in size as additional molecules of the material settle on it (Comptonıs). Sometimes the atoms can combine singly instead of first forming molecules to make a large crystalline mass (³Crystals²). For a crystal to be created in nature can last from ten years to ten centuries. These uniquely structured substances are used for many things. They are used in food, cutting, building, in the field of medicine, and in many other things. Not only are crystals useful in the everyday life of humans, but they are also beautiful creations of mother nature. In unassisted nucleation, molecules of the solute are in the solution. Most of the time the solute molecules only see the solvent molecules around them. Sometimes the solute molecules can see other solute molecules and they become attracted to one another if the compound is solid and pure (Dr. Boyle). These molecules will stay together for a little while and will eventually be separated by other internal forces. However, sometimes the molecules will stay together long enough to meet up with a third, then a fourth, and then even a fifth solute molecule. When this happens the combined attraction force eventually becomes stronger than the other forces within the solution (Dr. Boyle). This attraction force tends to disrupt the formation of these aggregates. When this happens a protocrystal or a pre-crystal becomes a nucleation site (Dr. Boyle). Dr. Boyle. ³ Frequently Asked Questions about Crystals for Students.² 14 Aug. 1998 .
Some common words found in the essay are:
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Approximate Word count = 1593
Approximate Pages = 6 (250 words per page double spaced)
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