MOLECULES AND MATERIALS

Question 1

three forms of the element carbon

Answer 1

Graphite, diamond, and fullerenes

Question 2

___________ was named buckminsterfullerene due to its resemblance to geodesic domes
popularized by the architect ___________

Answer 2

C60, Buckminster Fuller

Question 3

Fullerenes were discovered in _______ in the form of C60

Answer 3

1985

Question 4

Carbon has long been used as a material in important applications

Answer 4

• Diamond is used in drill bits and jewelry
• Graphite is used in pencils, as a lubricant, and as a composite material
• Applications of fullerenes and nanotubes are still being explored

Question 5

are maps showing which state or phase of a compound or an element will be most stable at a given combination of pressure and temperature

Answer 5

Phase Diagrams

Question 6

The state or phase of a compound can be manipulated by changing

Answer 6

the temperature and pressure of the compound

Question 7

Note that pressure is shown on a
______ scale

Answer 7

logarithmic

Question 8

are a type of fullerene that have remarkable properties

Answer 8

Nanotubes

Question 9

What property of carbon nanotubes might lead to interesting engineering
applications?
* Resistance to reactions
* Tensile strength
* Elasticity

Answer 9

• Tensile strength

Question 10

Atoms or molecules arrange themselves into two types of solids

Answer 10

Crystalline solids
Amorphous solids

Question 11

Atoms or molecules that assume a regular, repeating geometric arrangement

Answer 11

Crystalline solids

Question 12

Atoms or molecules that assume a random arrangement

Answer 12

Amorphous solids

Question 13

in crystalline solids, it is the percentage of space occupied in a given arrangement

Answer 13

Packing efficiency

Question 14

• The less empty space in the packing of atoms or molecules in a solid, the higher the packing efficiency

Answer 14

• The higher the packing efficiency, the higher the density of a solid

Question 15

Two ways to maximize packing efficiency

Answer 15

hexagonal close-packing or hcp
cubic close-packing or ccp

Question 16

the third layer can be stacked directly above the atoms in the first layer

Answer 16

hexagonal close-packing or hcp

Question 17

if the third layer can be stacked directly above the hollows in the first layer

Answer 17

cubic close-packing or ccp

Question 18

is the smallest collection of atoms that displays all the features of a crystal structure

Answer 18

unit cell

Question 19

Three types of cubic unit cells

Answer 19

simple cubic or sc
body-centered cubic or bcc
face-centered cubic or fcc

Question 20

1/8 each of eight corner atoms

Answer 20

simple cubic

Question 21

containing one additional atom within

Answer 21

body-centered cubic

Question 22

with an additional ½ each of six atoms along the faces

Answer 22

face-centered cubic

Question 23

How much does each atom at the corner of a cubic unit cell contribute to that
unit cell?
* 1 atom
* 1/4 atom
* 1/8 atom
* 1/12 atom

Answer 23

1/8 atom

Question 24

Calculation of Packing Efficiency

Answer 24

fcc = 1/2 (# of fc) + 1/8 (# of corner) = 4
bcc = (# of bcc) - 1/8 (# of corner) = 2
sc = 1/8 (# of corner) = 1

Question 25

is the number of atoms immediately adjacent to any given atom

Answer 25

Coordination number

Question 26

Condensed Phases—Solids * Simple cubic structure has a coordination number of __ * Body-centered cubic structure has a coordination number of __ * Close-packed structures, ccp and hcp, have coordination numbers of __

Answer 26

6, 8, 12

Question 27

are the attractive and repulsive forces between molecules

Answer 27

Intermolecular forces

Question 28

responsible for determining the structure and properties of condensed phases

Answer 28

Intermolecular forces

Question 29

are common to all molecules

Answer 29

Dispersion forces

Question 30

Dispersion forces are also called

Answer 30

London Forces

Question 31

Dispersion forces are also referred as

Answer 31

instantaneous dipole–induced dipole forces

Question 31

exist for two oppositely charged points separated by some distance

Answer 31

Dipoles

Question 32

occurs when a fluctuation in electron density for an atom or molecule produces a dipole

Answer 32

instantaneous dipole

Question 33

are short-lived and constantly forming and disappearing

Answer 33

Instantaneous dipoles

Question 34

is created when an external electric field forces a dipole to exist

Answer 34

induced dipole

Question 35

the source of the external electric field

Answer 35

permanent dipole

Question 36

is a measure of how susceptible a molecule’s electron density is to perturbation by external electric fields

Answer 36

Polarizability

Question 37

strength of a dispersion force can be estimated from

Answer 37

polarizability of a molecule

Question 38

are the attractive and repulsive forces for molecules with a permanent dipole

Answer 38

Dipole–dipole forces

Question 39

Molecules with larger dipoles have ________ dipole–dipole forces

Answer 39

stronger

Question 40

Dipole–dipole forces are typically ________ than dispersion forces

Answer 40

stronger

Question 41

are a special case of dipole–dipole forces

Answer 41

Hydrogen bonds

Question 42

occur only in compounds containing hydrogen, which is covalently bonded to the highly electronegative elements F, O, or N

Answer 42

Hydrogen bonds

Question 42

Intermolecular forces are ______ compared to the average covalent bond

Answer 42

weak

Question 43

Polyethylene forms by addition polymerization. How many C-C single bonds are likely to form n C=C double bonds that undergo the reaction? * n * 2n * 3n

Answer 43

2n

Question 44

is the gas phase pressure of a substance in dynamic equilibrium with the pure liquid in a pure substance

Answer 44

Vapor Pressure

Question 45

Liquids with high vapor pressures are described as

Answer 45

volatile

Question 46

To measure the vapor pressure of a solid or a liquid, the system must reach

Answer 46

equilibrium

Question 47

the temperature of a liquid at which its vapor pressure equals one atmospheric pressure (1 atm)

Answer 47

Normal boiling point

Question 48

is a liquid’s response to the imbalance in attractive forces and the tendency to minimize energy

Answer 48

Surface Tension

Question 49

have the greatest volumes with the least amount of surface area

Answer 49

Spherical shapes

Question 50

is the result of molecules at the surface of a liquid experiencing fewer intermolecular forces than liquid molecules inside the bulk liquid

Answer 50

Surface tension

Question 51

The interaction between a liquid and the surface of a solid depends on two types of attractive forces

Answer 51

Cohesion forces Adhesion forces

Question 52

are liquid–liquid interactions

Answer 52

Cohesion forces

Question 53

are liquid–solid interactions

Answer 53

Adhesion forces

Question 54

The relative strengths of the two forces dictate the shape of a liquid’s

Answer 54

meniscus

Question 55

Strong adhesion forces and weaker cohesion forces result in a

Answer 55

concave meniscus

Question 56

Weak adhesion forces and stronger cohesion forces result in a

Answer 56

convex meniscus

Question 57

A substance that has a low boiling point will also have a low value for which property? * Surface tension * Vapor pressure * Volatility

Answer 57

* Vapor pressure

Question 58

are giant molecules constructed by sequentially stringing together smaller molecules called monomers

Answer 58

Polymers

Question 59

Monomers containing one or more double bonds undergo free radical addition reactions to form

Answer 59

addition polymers

Question 60

Monomers containing one or more double bonds undergo ____________ to form addition polymers

Answer 60

free radical addition reactions

Question 61

Addition polymerization occurs through

Answer 61

initiation, propagation, and termination

Question 62

A free radical, species with an unpaired electron, is produced

Answer 62

Initiation

Question 63

The free radical attacks the double bond of the monomer to break the double bond, leaving a single bond

Answer 63

Propagation

Question 64

A free radical reacts with another free radical

Answer 64

Termination

Question 65

is a random event, not all polymer chains will have the same length

Answer 65

Termination

Question 66

All methyl groups are arranged on the same side of the polymer chain

Answer 66

Isotactic

Question 67

Methyl groups alternate systematically from one side of the polymer chain to the other

Answer 67

Syndiotactic

Question 68

Methyl groups are arranged randomly along the polymer chain

Answer 68

Atactic

Question 69

are formed when functional groups on the monomers react, linking the monomers together and producing water or another small molecule

Answer 69

Condensation polymers

Question 70

Which engineering application is most likely to use thermoplastic polymers? * Automobile engine * Asphalt road construction * Heating exhaust system * Consumer product packaging

Answer 70

* Consumer product packaging

Question 71

are made up of more than one type of monomer

Answer 71

Copolymers

Question 72

are monomers arranged in a regular, alternating series

Answer 72

Alternating copolymers

Question 73

are regions where a single monomer is repeated, interspersed with other regions where a different monomer is repeated

Answer 73

Block copolymers

Question 74

are those where monomers are arranged randomly

Answer 74

Random copolymers

Question 75

are those where monomers of different polymers are branched from a backbone of a different polymer

Answer 75

Graft copolymers

Question 76

polymers melt or deform on heating

Answer 76

Thermoplastic

Question 77

polymers maintain their shape and strength when heated

Answer 77

Thermosetting

Question 78

are added to polymers to modify polymer properties

Answer 78

Additives

Question 79

Conducting polymers are the subject of new materials research. What fundamental concept is being used to help understand the prospects for conducting polymers? * Electronegativity * Ionic bonding * Resonance * Thermosetting

Answer 79

* Resonance