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Name: Chris W.
Status: student
Age: 16
Location: N/A
Country: N/A
Date: 2/13/2004


Question:
What is a crystalline solid?


Replies:
Hello,

Crystalline solids are a class of solids that have regular or nearly regular crystalline structures. This means that the atoms in these solids are arranged in an orderly manner.

Examples of crystalline solids are sugar, sugar candy, or rock candy. Sugar powder (which is solid but is not considered crystalline) consists of small invisible grains which can be heated up and converted to visible sugar crystal (common sugar) or to larger rock candy crystals. The crystalline nature of rock candy makes it transparent whereas power sugar from which it was made and has the same sugar molecules is opaque.

Dr. Ali Khounsary
Argonne National Laboratory


Hi Chris!

Solid is the state of matter where the forming particles( atoms, molecules or ions) are arranged so closely that make it virtually incompressible. In many solids, the particles are arranged in regular, systematic patterns. When this happen the solids are said to be in crystalline state, or be a crystalline solid. Their structure, that is characteristic of the substance is called crystal structure, formed by a regular repetitive crystal lattice. A crystal lattice can be described in terms of small repeating tri-dimensional segments called unit cells. The sequence of these unit cells into space results in plane faces and definite angles between the faces. Such characteristics begin in molecular dimensions and repeat accordingly as the crystal grows up to macroscopic sizes. Good common examples are crystals of sodium chloride (table salt), quartz, diamond. Other solids that do not present that regularity (called symmetry) are the amorphous solids.

Thanks for asking NEWTON!

Mabel
(Dr. Mabel Rodrigues)


Chris,

Crystallinity implies that the sub-units that make up the crystal are arranged in a regular, repeating array within the lattice rather than being fixed in chaotic, random, disoriented locations. Though glass is a solid, it is not crystalline because the silica units are not boned to each other in a regular, uniform, repeatable array.

Regards,
ProfHoff 803


Very simply, it is a solid with a crystal form. This is usually part of the definition of "mineral." In a mineral, atoms bond together in certain ways, and the arrangement of atoms usually results in a crystal (a crystalline solid). Often, the crystal has a regular, easily recognized shape, such as a cube in halite (table salt). Sodium and chlorine arrange themselves in a cubic form and that is reflected in the outward appearance (it is not always true that the outward appearance reflects the internal chemistry). Sometimes the crystalline form is irregular and you cannot easily see the shape. Mineralogists are geologists who study minerals, their atomic arrangements, crystalline structures and shapes.

Pat Rowe


A crystalline solid is one in which the atoms and/or molecules are present and oriented in a repeating translational unit referred to as the "unit cell". This can be determined by the diffraction of x-rays which are scattered off the repeating sets of atoms in a fashion analogous to how light is scattered by a grating (e.g. look at a CD at a low angle and see the various colors of the rainbow). From the pattern of scattered x-rays it is possible to determine the structure of molecules in the crystal.

Vince Calder


Chris,

A crystalline solid is a material that has a definite orderly array of atoms, ions, or molecules, as would a pyramid of oranges or cannon-balls. The orderly arrangement of particles in a crystal is called a crystal lattice. Sand, salt, sugar, diamond, and graphite are examples of some common crystalline materials. Each crystalline material has a unique melting temperature. (Taken from Microsoft Encarta DVD 2004). I hope that this helps.

Sincerely,

Bob Trach



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