Crystal Classes

Question 1

Isometric

Answer 1

A=b=c
All axes = 90 degrees
example = cube, most symmetric

Question 2

orthorhombic

Answer 2

a≠ b≠ c
all axes = 90 degrees
4th most symmetric

Question 3

hexegonal

Answer 3

a = b = d 120 degrees between axes,
a, b, d are ⟂ to c
2nd most symmetric
6-fold

Question 4

monoclinic

Answer 4

a≠ b≠ c
β (angle between a and c) > 90
α (angle between b and c) = 90
λ (angle between a and b) = 90
2nd least symmetric

Question 5

tetragonal

Answer 5

a= b ≠ c
all axes are 90 degrees
3rd most symmetric

Question 6

Triclinic

Answer 6

a≠ b≠ c
β, α, λ ≠ 90
little to no symmetry (might have 1 mirror)

Question 7

general form

Answer 7

the form in which the faces intersect the axes at different lengths
{hkl} for isometric, hexagonal, tetragonal
{111} for orthorombic, monoclinic, triclinic

Question 8

Trigonal

Answer 8

a=b=d = 120 degrees =\ c
A,b,d perpendicular to c
2nd most symmetrical
(Similar to Hexagonal, except has only 1 3-fold axis)