Symmetry Elements

Question 1

Face centered lattice

Answer 1

F

Question 2

Primitive lattice

Answer 2

P

Question 3

Body centered lattice

Answer 3

I

Question 4

Base centered lattice

Answer 4

A,B,C

Question 5

Rhombohedral

Answer 5

R

Question 6

Rotational symmetry

Answer 6

Only 5 of the infinite rotational symmetries are consistent with translational symmetries.

6-, 4-, 3-, 2-, and 1- are the only ones that can fill 3-space

L.H. Thumb out —> L.H. Thumb in

Question 7

Mirror plane

Answer 7

m

L.H. Thumb out —> R.H. Thumb out

Question 8

Inversion Center

Answer 8

Like a 2-fold rotation + /m

Question 9

Roto-inversion

Answer 9

1-,2-,3-,4-,6- bar

Rotation followed by an inversion

Question 10

Screw axis

Answer 10

A(sub B)

Rotation and a translation

A = rotation by 360/A
B = translation by B/A

Question 11

Glide planes

Answer 11

a, b, c

Combines reflection and translation

Question 12

Net planes

Answer 12

n

Combines reflection and 2 translations

Question 13

Example: 2/m

Answer 13

Example: 2-fold rot. Axis perpendicular to a mirror plane

Question 14

Example: 4mm

Answer 14

4-fold rotational axis parallel to 2 mirror planes which are not symmetrically relates

Question 15

R(-3)c

Answer 15

Corundum space group

R = rhombohedral lattice type
(-3) = 3-fold roto-inversion axis
c = glide plane parallel to 3

Question 16

Pnma

Answer 16

Olivine point group
P = primitive lattice type
n = net plane perpendicular to x axis
m = mirror plane perpendicular to y axis
a = glide plane perpendicular to z