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level: Crystal types, systems and structures

Questions and Answers List

Question	Answer
Crystal ----- can be observed with eyes	types
In a crystal, all atoms are arranged in ....	a regular grid pattern (lattice)
This type of packed structures tends to have lower energies	Dense, ordered
What characteristic of non dense and random packed structures causes it to have higher energies	vibration of atoms
a = b = c α = β = γ = 90	cubic
a = b ≠ c α = β = γ = 90	tetragonal
a ≠ b ≠ c α = β = γ = 90	orthohombic
on it's side a = b = c α = β = γ ≠ 90	rhombohedral
a = b ≠ c α = β = 90 γ = 120	hexagonal
a ≠ b ≠ c α = γ = 90 ≠ β	monoclinic
a ≠ b ≠ c α ≠ β ≠ γ	triclinic
6 face atoms at 1/2 each 8 corner atoms at 1/8 each 4 atoms coordination number : 12	FCC ( face centered cubic)
1 center atom counts for 1 8 corner atoms at 1/8 each 2 atoms coordination number: 8	BCC (body centered cubic)
12 corner atoms at 1/6 each 2 face atoms at 1/2 each 3 internal atoms for 1 each 6 atoms coordination number: 12	HCP (hexagonal close packed)
number of nearest neighbor atoms surrounding an atom or ion	coordination number