Bonding

Question 1

3 primary bond types

Answer 1

Ionic
Covalent
Metallic

Question 2

2 secondary bond types

Answer 2

Van see waals

Hydrogen

Question 3

Main bonds in metals/alloys

Answer 3

Metallic

Question 4

Main bonds in ceramics

Answer 4

Ionic/ covalent

Question 5

Main bonds in polymers (2 aspects)

Answer 5

Covalent bonds between carbon atoms in chains

Van der waals or hydrogen bonds between chains

Question 6

Elastic modulus and melting point are a function of

Answer 6

Bond energy

Question 7

3 assumptions for materials structure

Answer 7

Atoms are close packed hard spheres
Atoms are packed two dimensionally in atomic planes
Planes are stacked to form crystals

Question 8

3 arrangements of atoms are

Answer 8

Face centered cubic
Hexagonal close packed
Body centred cubic

Question 9

Main features of FCC

Answer 9

Atom in each corner and on each face
Close packed
More slip directions so more ductile

Question 10

Main features of BCC

Answer 10

Atom on each corner. 1 atom in centre

Non close pack structure

Question 11

3 atom arrangements in order of ductility (best-worst)

Answer 11

FCC
BCC
HCP

Question 12

3 atom arrangements in order of strength (best-worst)

Answer 12

HCP
BCC
FCC

Question 13

What determines density( 3)

Which is most significant

Answer 13

Atomic weight ( most significant)
Size of atoms
Atom packing

Question 14

What does crystalline mean

Answer 14

Regularly repeating pattern of structural units

Most materials are crystalline

Question 15

FCC and HCP take up how much available space

Answer 15

74%

Question 16

BCC takes up how much available space

Answer 16

68%

Question 17

Ferrite (alpha) is iron at what temp with what packing

Answer 17

Room temp

BCC

Question 18

Austenite is iron at what temp and with what packing

Answer 18

Above 912 c

FCC

Question 19

Ferrite (delta)is iron at what temp and with what packing

Answer 19

Above 1394 c

BCC

Question 20

Above what temp does iron become liquid

Answer 20

1538

Question 21

Why do u quench iron

Answer 21

Stops carbon diffusion

Creates new structure which is harder to deform

Question 22

What is another name for noncrystalline

Answer 22

Amorphous

Question 23

Key feature of metallic crystal structure and 3 reasons why

Answer 23

Densely packed as
Only 1 element so atomic radii is constant
Metallic bonding is not directional
Electron clouds shield cores from each other

Question 24

Atomic packing in glasses

Answer 24

Base often amorphous silica

Rapid cooling means the amorphous structure achieved by melting is maintained

Question 25

Crystal structure of ceramics (?2 main facts)

Answer 25

Composed of at least 2 elements

Have cations and anions

Question 26

Most materials are polycrystalline. Each crystal is called a …. with …. separating each one

Answer 26

Grain

Grain boundaries

Question 27

4 crystalline imperfections

Answer 27

Vacancies
Solute atoms
Dislocations
Grain boundaries

Question 28

Polymers are made up of….

they can be either …. or ….

Answer 28

Long chains of carbon atoms

Amorphous, crystalline or both

Question 29

Polymorphism is

Answer 29

When materials change from one structure to another

Question 30

Fullerenes are

Answer 30

Spherical cluster of 60 carbon atoms

Question 31

Carbon nanotubes are

Answer 31

Sheet of graphite rolled into a tube. The ends are capped with fullerene hemispheres

Question 32

Graphene is

Answer 32

A single atomic layer of graphite composer of hexagonally bonded carbon atoms

Question 33

Diamond is only …. at

Answer 33

Meta stable

Room temp and pressure

Question 34

Shape memory alloys are

Answer 34

Materials that show a memory when they are deformed /heated/ cooled due to reversible change in structure