Unit 1 : Basic Concepts of Crystal Structure

Question 1

minerals formed underground from three-dimensional repeating patterns of atoms.

Answer 1

Crystals

Question 2

the experimental science of determining the arrangement of atoms
in crystalline solids.

Answer 2

Crystallography

Question 3

a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered

Answer 3

A Crystal or Crystalline Solid

Question 4

The smallest group of particles in the material that constitutes the repeating pattern is the unit cell of the structure.

Answer 4

Unit Cell

Question 5

describes the periodic repetition of a structural feature across a length or through an area or volume.

Answer 5

Translational symmetry

Question 6

describes the periodic repetition of a structural feature around a point.

Answer 6

Point symmetry

Question 7

occurs when the structure features on one side of a plane passing through the center of a crystal are the mirror image of the structural features on the other side.

Answer 7

Reflection

Question 8

Describes the repetition of a motif or structural feature around a single reference point, commonly the center of a unit cell or a crystal.

Answer 8

Point symmetry

Question 9

executable shifting movements, proceeding along a straight line and on a certain specified distance, such that the operation does not result in any change of the shifted pattern.

Answer 9

Translational symmetry

Question 10

arises when a structural element is rotated a fixed number of degrees about a central point and then repeated.

Answer 10

Rotational symmetry

Question 11

any line which is drawn through the origin at the center of the crystal will connect two identical features on opposite sides of the Reflection in a point (Center of Symmetry)

Answer 11

inversion symmetry

Question 12

a compound symmetry operation which is produced by performing a rotation followed by an inversion.

Answer 12

Rotoinversion

Question 13

The crystal class which possesses the highest possible symmetry or the highest number of symmetry elements within each system is

Answer 13

holomorphic class

Question 14

a set of faces which are geometrically equivalent and whose spatial positions are related to one another according to the symmetry of the crystal.

Answer 14

Crystal form

Question 15

also called a pedion. It consists of a single face which is geometrically unique for the crystal and is not repeated by any set of symmetry operations.

Answer 15

Monohedron

Question 16

also called a pinacoid. It consists of two and only two geometrically equivalent faces which occupy opposite sides of a crystal.

Answer 16

Parallelohedron

Question 17

consists of two and only two nonparallel geometrically equivalent faces.

Answer 17

Dihedron

Question 18

possess two sets of nonparallel geometrically equivalent faces, each of which is related by a 2-fold rotation.

Answer 18

Disphenoid

Question 19

composed of a set of 3, 4, 6, 8, or 12 geometrically equivalent faces which are all parallel to the same axis.

Answer 19

Prism

Question 20

composed of a set of 3, 4, 6, 8, or 12 faces which are not parallel but instead intersect at a point.

Answer 20

Pyramid

Question 21

composed of two pyramids placed base-to-base and related by reflection across a mirror plane which runs parallel to and adjacent
to the pyramid bases.

Answer 21

Dipyramid

Question 22

the ability of a solid material to exist in more than one form or crystal structure.

Answer 22

polymorphism