Exam 1 Review

Question 1

Amorphous materials can have a BCC crystal structure

Answer 1

False, amorphous materials lack a defined crystal structure. Atoms are arranged randomly with no repeating patterns.

Question 2

What is a mechanical property a response to?

Answer 2

An applied load

Question 3

What is an optical property a response to?

Answer 3

Light

Question 4

What is a deteriorative property a response to?

Answer 4

Chemical reactivity

Question 5

What are the characteristics of a polymer?

Answer 5

Plastics or rubbers. Organic compounds (C,H) and other non-metallic elements (O,N). Large Chain-like structures. Strong but lightweight.

Question 6

What are the four molecular structures of polymers?

Answer 6

Linear, branched, crosslinked, and network

Question 7

In a FCC lattice, the atoms touch along the

Answer 7

face diagonal

Question 8

True or False: a weakly bonded material will have a shallower energy well and more gradual dF/dr slope

Answer 8

True

Question 9

What are the four types of copolymers?

Answer 9

Random, alternating, block, graft

Question 10

If a plane unit cell does not intersect a specific axis, the intercept for that axis is

Answer 10

Infinite

Question 11

True or false: A deep, narrow energy well likely indicates that a material has a low coefficient of thermal expansion.

Answer 11

True

Question 12

True or false: Van der Waals are not a primary bond

Answer 12

True

Question 13

What does it mean that ionic bonding is non-directional?

Answer 13

The magnitude of the bond is equal in all directions around an ion.

Question 14

True or False: for ionic materials to be stable, all positive ions must have negatively charged ions as nearest neighbors in a three dimensional scheme.

Answer 14

True

Question 15

True or false: Positive and negative ions attract one another due to a difference in their net electrical charge.

Answer 15

True

Question 16

What are the types of primary bonds?

Answer 16

Ionic, covalent, metallic

Question 17

What are the types of secondary bonds?

Answer 17

Van der Waals, dipole, hydrogen honding

Question 18

What are the types of secondary bonding?

Answer 18

Van der Waals, dipole, hydrogen bonding

Question 19

Does this describe a schotty or frenkel defect: Vacancies in both the cations and anions in the correct ratio to maintain neutrality.

Answer 19

Schotty defect

Question 20

Does this describe a Schotty or Frenkel defect: Formed when a cation leaves its lattice site and moves to an interstitial space, no change in charge?

Answer 20

Frenkel defect

Question 21

The stronger the bond, the _____ the modulus, the _____ the CTE, and the _____ the heat of fusion?

Answer 21

higher, lower, higher

Question 22

The slope of the bond-force curve at r0 allows you to measure the material’s ___?

Answer 22

stiffness

Question 23

Name the criteria for a substantial solid solution (Hume-Rothery Rules)

Answer 23

Size difference of <15%, same crystal structure, similar valence, similar electronegativity

Question 24

The primary bonding in plastics is

Answer 24

covalent

Question 25

ceramic structures are composed of

Answer 25

ions

Question 26

What is composed of metallic and non-metallic elements held together by ionic bonds?

Answer 26

Ceramics

Question 27

True or false: a FCC is more densely packed than a BCC.

Answer 27

True

Question 28

What is the coordination number of a crystal structure?

Answer 28

The number of nearest neighbor atoms.

Question 29

What is the degree of polymerization?

Answer 29

The number of repeat units in the polymer, denoted by n.

Question 30

What is polymorphism?

Answer 30

The fact that some metals and non metals may have more than one crystal structure.

Question 31

What is N sub v?

Answer 31

The equilibrium number of vacancies

Question 32

What is N?

Answer 32

The total number of atomic sites.

Question 33

What is k?

Answer 33

Boltzmann’s constant (eV/atom K)

Question 34

What is T?

Answer 34

temperature (in K)

Question 35

What is N sub a?

Answer 35

Avogradro’s number

Question 36

What is A?

Answer 36

the atomic weight (g/mol)

Question 37

What is N measured in?

Answer 37

atoms/cubic centimeter

Question 38

What can the addition of an impurity lead to?

Answer 38

A solid solution or anew phase

Question 39

What is the solute/impurity atom in a solid solution?

Answer 39

The atom present in the least amount.

Question 40

What is M sub i?

Answer 40

Mean molecular weight of size range “i”

Question 41

What is X sub i?

Answer 41

The fraction of the size range

Question 42

What is N sub i?

Answer 42

number of chains with Mw Mi