Crystal Structure

Question 1

Two Types of Solid

Answer 1

Crystalline and Amorphous

Question 2

Properties of crystalline solids depend on the _________ or the manner in which
atoms, ions, or molecules are spatially arranged

Answer 2

crystal
structure of the material,

Question 3

is a periodic arrangement of
points in space with respect to three dimensional
network of lines

Answer 3

Space Lattice or Lattice

Question 4

________ – the space covered by the lattice
points

Answer 4

Lattice Space

Question 5

_______ – each atom represented by a point,
where the network lines intersect

Answer 5

Lattice Point

Question 6

________ arrangement of lattice points

Answer 6

Lattice Array

Question 7

________ Tiny blocks formed by arrangements of small
groups of atoms

Answer 7

Unit Cell

Question 8

Chosen to represent the symmetry of a crystal
structure, and may be defined as:

Answer 8

1. Finite representation of infinite lattice
2. Small repeat entity
3. Basic structural unit
4. Building block of crystal structure

Question 9

Lattice Parameters
 Six lattice parameters are: ____________
 Typically in the order of few Angstroms (Å), equal to
__________
 Based on the length equality or inequality and the
orientation (the angles between them, α, β, and γ) a
total of _________ can be defined

Answer 9

a, b, c, α, β, and γ.
0.1 nanometer
7 crystal systems

Question 10

Bravais Lattices
 ____ types of crystal
systems where
presented, with the
inclusion of the
property of Centering
 Types of Centering
___________

Answer 10

14
1. Face-Centered
2. Body-Centered
3. Base-Centered

Question 11

______________
* Atoms are arranged at the corners of the cube
with another atom at the cube center
*
Has 2 atoms in one unit cell.
* Examples: alpha iron, chromium, tungsten, tantalum,
and molybdenum
» Center and corner atoms touch one another along
cube diagonals, and unit cell length o and atomic

Answer 11

Body-Centered Cubic (BCC)

Question 12

_________
 Most elementary crystal structure with
three mutually perpendicular axes
arbitrarily placed through one of the
corners of a cell.
 Each corner is occupied with ____
 Only _____ is packed in this
manner
 Packing density is relatively ______

Answer 12

Simple Cubic (SC)
one atom
polonium
low

Question 13

Hexagonal Closed-Pack (HCP)
Cell of an HCP lattice is visualized as a top and
bottom plane of ______, forming a regular hexagon
around a central atom. In between, these planes is a
half-hexagon of _________. D
There are two lattice parameters in HCP, a and c,
representing the basal and height parameters
☐ respectively.
AU
Has ______ per unit cell.
Examples: zinc, lithium, magnesium, beryllium

Answer 13

7 atoms
3 atoms
6 atoms

Question 14

_______
 a line or vector directed between
two points
 directions are given by specifying
the coordinates (x, y, z) of a point on
a vector (Pxyz) passing through the
origin
 Notation: ______

Answer 14

Crystallographic Direction
[xyz]

Question 15

__________ is the number of nearest neighbor atoms or ions surrounding an atom or ion. For
FCC and HCP systems, the coordination number is ____. For BCC, it’s__. For SC, coordination number is
____.

Answer 15

Coordination number
12
8
6

Question 16

___________ indicates how closely atoms are packed in a unit
cell and is given by the ratio of volume of atoms in the unit cell and volume of the unit cell.

Answer 16

Atomic packing factor (APF) or packing efficiency

Question 17

APF = ______________
SC = _________
FCC = HCP = ________________
BCC = __________

Answer 17

“Volume of atoms” /”Volume of unit cell”
0.52 or 52%
0.74 or 74% (26% void space in unit cell)
0.68 or 68%

Question 18

refers to density of atomic packing on a particular plane

number of atoms on a plane / area of plane

Answer 18

Planar Density

Question 19

number of atoms on the direction vector / length of the direction vector

Answer 19

Linear density