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this is not a level but uni work.
definition of a unit cell.
Has more than one lattice point and defines a small region which is repeated throughout the crystal
Name three cuboidal crystal systems
Cubic, tetragonal and orthorhombic
Describe the parameter of a cubic unit cell.
Include its edge length, which is equal in all three sides, and the angles between the edges, which are all 90 degrees. Additionally, the cubic unit cell has a coordination number of 8 - is surrounded by 8 others.
Describe the parameters of a tetragonal unit cell.
Include its edge lengths, where one edge length is different from the other two, which are equal, and the angles between the edges, which are all 90 degrees. The coordination number is typically 8.
Define the parameters of an orthorhombic unit cell
Include three unequal edge lengths, all of which intersect at 90 degrees. The coordination number is usually 4 or 8, depending on the crystal structure.
State 2 other high symmetry crystal systems
Hexagonal and rhombohedral
Describe the parameters of a hexagonal cubic cell.
Include two equal edge lengths and one different edge length, with angles of 120 degrees between the equal edges and 90 degrees between the unequal edge and the other two. The coordination number is 12.
Describe the parameters of a rhombohedral unit cell
Consist of three equal edge lengths and angles all being equal but not right angles. The coordination number is 6.
State and describe 2 low symmetry crystal systems
Monoclinic and triclinic. Monoclinic has unequal edge lengths with one angle not equal to 90 degrees, while triclinic has all edges and angles unequal.
