Lesson 7

Question 1

Categories of Solids

Answer 1

Crystalline Solid

Amorphous Solid

Question 2

a solid that Has rigid and long-range order and its atoms, molecules, or ions occupy specific
positions.

Answer 2

crystalline solid

Question 3

In crystalline solid, The arrangement of particles is such that the net attractive intermolecular forces
are at their ___________.

The molecular forces responsible for the stability of a crystal can be ionic forces,
covalent bonds, van der Waals forces, hydrogen bonds, or a combination of these
forces.

Answer 3

maximum

Question 4

A solid where there is an absence of a well-defined arrangement and long-range
molecular order

Answer 4

amorphous solid

Question 5

Atoms or ions (described as crystalline structures) are thought of as being solid
spheres having well-defined diameters. This is known as the ____________ in which spheres representing
nearest-neighbor atoms touch one another.

Answer 5

atomic hard-sphere model

Question 6

means a three- dimensional array of points coinciding with atom positions or
sphere centers.

Answer 6

lattice

Question 7

A __________ is the basic structural (repeating) unit of a crystalline solid.

Answer 7

unit cell

Question 8

Angle α is defined by edges ________
Angle β by edges _______
Angle γ by edges__________

Answer 8

-b and c
-a and c
-a and b

Question 9

The Seven Types of Unit Cells

Answer 9

simple cubic
tetragonal
orthorhombic
rhombohedral
monoclinic
triclinic
hexagonal

Question 10

____________ is a crystal structure with atoms located at each of
the corners and the center of all the cube faces.

Answer 10

face-centered cubic (FCC)

Question 11

Some familiar metals having this crystal structure are ___________________

Answer 11

copper, aluminum, silver, and
gold.

Question 12

The is a crystal structure with atoms located at each of
the corners and the center of all the cube faces.

Answer 12

face-centered cubic (FCC)

Question 13

FCC area formula

Answer 13

a=2Rsqrt2

Question 14

number of atoms per unit cell formula

Answer 14

Ni + (Nf/2)+(Nc/8)

Question 15

Number of atoms in FCC

Answer 15

4

Question 16

Two Important Characteristics of Crystal Structure

Answer 16

-coordination number
-atomic packing factor

Question 17

______________ (for metals) wherein each atom has the same
number of nearest-neighbor or touching atoms;

Answer 17

coordination number

Question 18

is the sum of the sphere volumes of
all atoms within a unit cell (assuming the atomic hard-sphere model) divided
by the unit cell volume.

Answer 18

atomic packing factor

Question 19

apf formula

Answer 19

volume of the atoms in a unit cell/ total unit of cell volume

Question 20

apf of fcc

Answer 20

0.74

Question 21

_____________ is a crystal structure that has a cubic unit cell with atoms located at all eight corners and a single atom
at the center of the cube.

Answer 21

body-centered cubic (BCC)

Question 22

bcc area

Answer 22

4R/sqrt3

Question 23

number of atoms of bcc

Answer 23

2

Question 24

atomic packing factor of bccsimple cubic (SC) crystal structure.

Answer 24

0.68

Question 25

The possibility of a unit cell that consists of atoms placed only at the corners of a cube
do exist and it is called the ___________

Answer 25

simple cubic (SC) crystal structure.

Question 26

the only simple-cubic element that has a
relatively low atomic packing factor.

Answer 26

polonium

Question 27

In the _____________________, the top and bottom faces of
the unit cell is consist of six atoms that form regular hexagons and surround a single
atom in the center.

Answer 27

hexagonal close-pack crystal structure (HCP)

Question 28

number of atoms in hexagonal close-pack crystal structure (HCP)

Answer 28

6

Question 29

refers to the scattering of X-rays by the units of a crystalline solid.

Answer 29

x-ray diffraction

Question 30

In 1912, _______, a German physicist recommended that
since the wavelength of X-rays is comparable in magnitude to the
distances between lattice points in a crystal, then the lattice
should be able to diffract X-rays.

Answer 30

Max von Laue

Question 31

Constructive interference (a) and destructive interference (b)

Answer 31

constructive: same direction kaya may sum
destructive: iba direction kayawalang sum

Question 32

Atoms in the
crystal absorb some of the
incoming radiation and then
reemit it; the process is called
the ______________

Answer 32

scattering of X rays.

Question 33

An ____________ basically tells us the relative electron densities at
various locations in a molecule.

Answer 33

electron-density contour map