Chapter 14

Question 1

hydrocarbons

Answer 1

composed of hydrogen and carbon

Question 2

unsaturated

Answer 2

molecules that have double and triple covalent bonds

Question 3

saturated

Answer 3

all bonds are single ones and no new atoms may be joined without the removal of others that are already bonded

Question 4

isomerism

Answer 4

hydrocarbon compounds with the same composition may have different atomic arrangements

Question 5

macromolecules

Answer 5

gigantic in comparison to the hydrocarbon molecules

Question 6

repeat units

Answer 6

long molecules that are successively repeated along the chain

Question 7

monomer

Answer 7

small molecule from which a polymer is synthesized

Question 8

polymer

Answer 8

many units

Question 9

homopolymer

Answer 9

when all of the repeating units along a chain are of the same type

Question 10

copolymers

Answer 10

chains composed of two or more different repeat units

Question 11

bifunctional

Answer 11

monomers that have an active bond that may react to form two covalent bonds with other monomers forming a two-dimensional chainlike molecular structure

Question 12

functionality

Answer 12

number of bonds that a given monomer can form

Question 13

trifunctional

Answer 13

three active bonds, from which a three-dimensional molecular network structure results

Question 14

linear polymers

Answer 14

those in which the repeat units are joined together end to end in single chains

Question 15

branched polymers

Answer 15

polymers synthesized in which side-branch chains are connected to the main ones

Question 16

crosslinked polymers

Answer 16

adjacent linear chains are joined one to another at various positions by covalent bonds

Question 17

network polymers

Answer 17

multifunctional monomers forming three or more active covalent bonds make 3D networks

Question 18

stereoisomerism

Answer 18

situation in which atoms are linked together in the same order (head-to-tail) but differ in their spatial arrangement

Question 19

isotactic configuration

Answer 19

all of the R groups are situated on the same side of the chain

Question 20

syndiotactic configuration

Answer 20

R groups alternate sides of the chain

Question 21

atactic configuration

Answer 21

random positioning

Question 22

cis structure

Answer 22

-for polymers, a prefix denoting a type of molecular structure
-for some unsaturated carbon chain atoms within a
repeat unit, a side atom or group may be situated on one side of the double bond or directly opposite at a 180 degree rotation position.
-in a cis structure, two such side groups within the same repeat unit reside on the same side

Question 23

trans structure

Answer 23

for polymers, a prefix denoting a type of molecular
structure
-for some unsaturated carbon chain atoms within a repeat unit, a single side atom or group may be situated on one side of the double bond, or directly opposite at a 180 degree rotation position
-in a trans structure, two such side groups within the same repeat unit reside on opposite sides

Question 24

thermoplastics

Answer 24

• soften when heated (and eventually liquefy) and harden when cooled—processes that are totally reversible and may be repeated
• most linear polymers and those having some branched structures with flexible chains

Question 25

thermosets

Answer 25

- network polymers | - become permanently hard during their formation and do not soften upon heating

Question 26

random copolymer

Answer 26

two different units are randomly dispersed along the chain

Question 27

alternating copolymer

Answer 27

two repeat units alternate chain positions

Question 28

block copolymer

Answer 28

identical repeat units are clustered in blocks along the chain

Question 29

graft copolymer

Answer 29

homopolymer side branches of one type may be grafted to homopolymer main chains that are composed of a different repeat unit

Question 30

polymer crystallinity

Answer 30

packing of molecular chains to produce an ordered atomic array

Question 31

ceramics and polymers

Answer 31

- ceramics = all crystalline except for glass because its amorphous - polymers = semi crystalline

Question 32

amorphous

Answer 32

no crystalline structure

Question 33

crystallite

Answer 33

a region within a crystalline polymer in which all the | molecular chains are ordered and aligned

Question 34

chain-folded model

Answer 34

for crystalline polymers, a model that describes the structure of platelet crystallites. Molecular alignment is accomplished by chain folding that occurs at the crystallite faces

Question 35

spherulite

Answer 35

an aggregate of ribbon-like polymer crystallites | (lamellae) radiating from a common central nucleation site; the crystallites are separated by amorphous regions