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ENGCHEM 111 LEC > MOLECULES AND MATERIALS > Flashcards

MOLECULES AND MATERIALS Flashcards

1
Q

three forms of the element carbon

A

Graphite, diamond, and fullerenes

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2
Q

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

A

C60, Buckminster Fuller

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3
Q

Fullerenes were discovered in _______ in the form of C60

A

1985

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4
Q

Carbon has long been used as a material in important applications

A
  • 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
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5
Q

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

A

Phase Diagrams

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6
Q

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

A

the temperature and pressure of the compound

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7
Q

Note that pressure is shown on a
______ scale

A

logarithmic

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8
Q

are a type of fullerene that have remarkable properties

A

Nanotubes

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9
Q

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

A
  • Tensile strength
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10
Q

Atoms or molecules arrange themselves into two types of solids

A

Crystalline solids
Amorphous solids

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11
Q

Atoms or molecules that assume a regular, repeating geometric arrangement

A

Crystalline solids

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12
Q

Atoms or molecules that assume a random arrangement

A

Amorphous solids

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13
Q

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

A

Packing efficiency

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14
Q
  • The less empty space in the packing of atoms or molecules in a solid, the higher the packing efficiency
A
  • The higher the packing efficiency, the higher the density of a solid
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15
Q

Two ways to maximize packing efficiency

A

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

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16
Q

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

A

hexagonal close-packing or hcp

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17
Q

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

A

cubic close-packing or ccp

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18
Q

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

A

unit cell

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19
Q

Three types of cubic unit cells

A

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

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20
Q

1/8 each of eight corner atoms

A

simple cubic

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21
Q

containing one additional atom within

A

body-centered cubic

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22
Q

with an additional ½ each of six atoms along the faces

A

face-centered cubic

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23
Q

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

A

1/8 atom

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24
Q

Calculation of Packing Efficiency

A

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

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25
Q

is the number of atoms immediately adjacent to any given atom

A

Coordination number

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26
Q

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 __
A

6, 8, 12

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27
Q

are the attractive and repulsive forces between molecules

A

Intermolecular forces

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28
Q

responsible for determining the structure and properties of condensed phases

A

Intermolecular forces

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29
Q

are common to all molecules

A

Dispersion forces

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30
Q

Dispersion forces are also called

A

London Forces

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31
Q

Dispersion forces are also referred as

A

instantaneous dipole–induced dipole forces

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31
Q

exist for two oppositely charged points separated by some distance

A

Dipoles

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32
Q

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

A

instantaneous dipole

33
Q

are short-lived and constantly forming and disappearing

A

Instantaneous dipoles

34
Q

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

A

induced dipole

35
Q

the source of the external electric field

A

permanent dipole

36
Q

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

A

Polarizability

37
Q

strength of a dispersion force can be estimated from

A

polarizability of a molecule

38
Q

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

A

Dipole–dipole forces

39
Q

Molecules with larger dipoles have ________ dipole–dipole forces

A

stronger

40
Q

Dipole–dipole forces are typically ________ than dispersion forces

A

stronger

41
Q

are a special case of dipole–dipole forces

A

Hydrogen bonds

42
Q

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

A

Hydrogen bonds

42
Q

Intermolecular forces are ______ compared to the average covalent bond

A

weak

43
Q

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

A

2n

44
Q

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

A

Vapor Pressure

45
Q

Liquids with high vapor pressures are described as

A

volatile

46
Q

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

A

equilibrium

47
Q

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

A

Normal boiling point

48
Q

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

A

Surface Tension

49
Q

have the greatest volumes with the least amount of surface area

A

Spherical shapes

50
Q

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

A

Surface tension

51
Q

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

A

Cohesion forces
Adhesion forces

52
Q

are liquid–liquid interactions

A

Cohesion forces

53
Q

are liquid–solid interactions

A

Adhesion forces

54
Q

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

A

meniscus

55
Q

Strong adhesion forces and weaker cohesion forces result in a

A

concave meniscus

56
Q

Weak adhesion forces and stronger cohesion forces result in a

A

convex meniscus

57
Q

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

A
  • Vapor pressure
58
Q

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

A

Polymers

59
Q

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

A

addition polymers

60
Q

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

A

free radical addition reactions

61
Q

Addition polymerization occurs through

A

initiation, propagation, and termination

62
Q

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

A

Initiation

63
Q

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

A

Propagation

64
Q

A free radical reacts with another free radical

A

Termination

65
Q

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

A

Termination

66
Q

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

A

Isotactic

67
Q

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

A

Syndiotactic

68
Q

Methyl groups are arranged randomly along the polymer chain

A

Atactic

69
Q

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

A

Condensation polymers

70
Q

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

A
  • Consumer product packaging
71
Q

are made up of more than one type of monomer

A

Copolymers

72
Q

are monomers arranged in a regular, alternating series

A

Alternating copolymers

73
Q

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

A

Block copolymers

74
Q

are those where monomers are arranged randomly

A

Random copolymers

75
Q

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

A

Graft copolymers

76
Q

polymers melt or deform on heating

A

Thermoplastic

77
Q

polymers maintain their shape and strength when heated

A

Thermosetting

78
Q

are added to polymers to modify polymer properties

A

Additives

79
Q

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

A
  • Resonance

ENGCHEM 111 LEC (13 decks)

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