CHM 11500 Lecture Notes - Lecture 27: Cubic Crystal System, Sodium Chloride
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4 Aug 2015
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CHM 155 - Lecture 27 - Crystal Structures
Crystalline Solids
● When many liquids cool, they freeze to form crystalline solids
● Crystalline solids are solids in which the particles are arranged in a definite
repeating pattern
● Some crystalline solids consist of one crystal (such as diamonds or salt particles)
while other crystalline solids are conglomerations of many crystals (such as
chunks of ice or metals)
● Amorphous solids are the opposite of crystalline solids: their particles do not
move readily while freezing and so become frozen in random positions resulting
in a disordered internal structure
○ Amorphous solids include glass, wax, and plastics
● There are several types of crystalline solids:
Unit Cells
● A unit cell is the repeating unit that creates the organized pattern present in a
crystalline solid
● A space lattice is “the collection of all the points in a crystal that have identical
environments”
●
The unit cell is the portion of the space lattice that will generate the entire lattice if
repeated