Book: Key Terms: 12

Question 1

amorphous solid

Answer 1

Have poorly defined shapes because their particles do not have an orderly arrangement throughout a sample.

Question 2

atomic solid

Answer 2

Individual atoms held together only by dispersion forces. Noble gases are the only substances that form such solids.

Question 3

band theory

Answer 3

Molecular orbital (MO) theory offers this more quantitative model of metallic bonding. The energies of the MOs are so close that they form a continuum, or band, of MOs.

Question 4

body-centered cubic unit cell

Answer 4

Identical particles lie at each corner and in the center of the cube. Coordination number is 8.

Question 5

boiling point

Answer 5

The temperature at which the vapor pressure inside the bubbles in the liquid equals the external pressure.

Question 6

branch

Answer 6

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Question 7

capillarity

Answer 7

The rising of a liquid against the pull of gravity through a narrow space, such as a thin tube. Results from the competition between the intermolecular forces within the liquid (cohesive forces) and those between the liquid and the tube walls (adhesive forces).

Question 8

Clausius-Clapeyron equation

Answer 8

Two versions: the one-point and the two-point
one-point: ln(P) = (-∆H_vap / R) (1/T) + C
two-point: ln(P_2/P_1) = (-∆H_vap / R) (1/T_2 - 1/T_1)

Question 9

condensation

Answer 9

As temperature drops, molecules in the gas phase come together and form a liquid.

Question 10

conduction band

Answer 10

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Question 11

conductor

Answer 11

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Question 12

coordination number

Answer 12

A parameter of any lattice. It is the number of nearest neighbors of a particle in a crystal.

Question 13

copolymer

Answer 13

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Question 14

critical point

Answer 14

A point of pressure and temperature where the densities of a heated liquid and the vaporized liquid are equal and the boundary between gas and liquid is blurred, with the phase boundary disappearing.

Question 15

crosslink

Answer 15

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Question 16

crystal defect

Answer 16

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Question 17

crystalline solid

Answer 17

have well-defined shapes because their particles—atoms, molecules, or ions—occur in an orderly arrangement.

Question 18

cubic closest packing

Answer 18

An arrangement based on the face-centered cubic unit cell which is the most efficient packing of particles in the cubic lattice.

Question 19

degree of polymerization

Answer 19

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Question 20

deposition

Answer 20

Phase change of a gas directly into a solid.

Question 21

dipole-dipole forces

Answer 21

A type of intermolecular force arising due to the electric field produced by polar molecules arranging the atoms and pulling them together.

Question 22

dispersion (London) forces

Answer 22

An intermolecular force present in all particles which results from the movement of electrons.

Question 23

doping

Answer 23

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Question 24

elastomer

Answer 24

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Question 25

face-centered cubic unit cell

Answer 25

Identical particles lie at each corner and in the center of each face but not the center of the cube. Coordination number is 12.

Question 26

freezing

Answer 26

As temperature drops, particles in a liquid move more slowly and become fixed in position, forming a solid.

Question 27

fusion

Answer 27

Phase change from a solid to a liquid—essentially melting.

Question 28

heat of fusion

Answer 28

The standard enthalpy change associated with a phase change between a solid and a liquid.

Question 29

heat of sublimation

Answer 29

The standard enthalpy change associated with a phase change between a solid and a gas.

Question 30

heat of vaporization

Answer 30

The standard enthalpy change associated with a phase change between a gas and a liquid.

Question 31

heating-cooling curve

Answer 31

Shows the changes in temperature of a sample when heat is absorbed or released at a constant rate.

Question 32

hexagonal closest packing

Answer 32

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Question 33

hydrogen bond (H bond)

Answer 33

A special and extremely strong dipole-dipole force which arises when an H atom is bonded with N, F, or O, which are highly electronegative.

Question 34

insulator

Answer 34

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Question 35

intermolecular forces

Answer 35

A form of potential energy that tends to draw molecules together.

Question 36

ion-dipole force

Answer 36

When an ion and a nearby polar molecule (dipole) attrach each other.

Question 37

ionic solid

Answer 37

binary ionic compounds form ionic solids, which are lattices.

Question 38

lattice

Answer 38

a collection of points which form a regular pattern

Question 39

liquid crystal

Answer 39

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Question 40

London force

Answer 40

dispersion forces.

Question 41

macromolecule

Answer 41

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Question 42

melting point

Answer 42

The kinetic energy of particles, via heat, is increased until they can break free of their fixed positions and flow freely. When the temperature is at the melting point, additional heat will go into breaking the fixed positions up, and at the melting point, there will be dynamic equilibrium as the melting rate equals the freezing rate.

Question 43

melting (fusion)

Answer 43

fusion

Question 44

metallic solid

Answer 44

Powerful metallic bonding forces fix metallic elements into crystals called metallic solids.

Question 45

molecular solid

Answer 45

A crystalline structure in which molecules occupy the lattice points.

Question 46

monomer

Answer 46

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Question 47

nanotechnology

Answer 47

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Question 48

network covalent solid

Answer 48

Strong covalent bonds link the atoms together and separate particles are not present in these.

Question 49

packing efficiency

Answer 49

The percentage of the total volume of the unit cell occupied by the spheres (atoms) themselves.

Question 50

phase

Answer 50

A physically distinct, homogeneous part of a system.

Question 51

phase change

Answer 51

liquid to solid, solid to gas, etc.

Question 52

phase diagram

Answer 52

Combines the liquid-gas, solid-liquid, and solid-gas curves and gives the conditions of temperature and pressure at which each phase is stable and at which phase changes occur.

Question 53

plastic

Answer 53

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Question 54

polarizability

Answer 54

A measure of how easily the electron cloud of an atom (or ion) can be distorted.

Question 55

polymer

Answer 55

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Question 56

radius of gyration

Answer 56

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Question 57

random coil

Answer 57

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Question 58

scanning tunneling microscopy

Answer 58

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Question 59

semiconductor

Answer 59

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Question 60

simple cubic unit cell

Answer 60

The centers of eight identical particles occupy the corners of a cube.

Question 61

sublimation

Answer 61

The direct phase change from a solid to a gas.

Question 62

superconductivity

Answer 62

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Question 63

surface tension

Answer 63

The energy required to increase the surface area by a given amount and has units of J/m^2

Question 64

triple point

Answer 64

the point of intersection on a phase diagram between the three phase-transition curves.

Question 65

unit cell

Answer 65

The smallest portion of a crystal that yields the crystal if it is repeated in all directions.

Question 66

valence band

Answer 66

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Question 67

van der Waals radius

Answer 67

one-half the closest distance between the nuclei of identical, non-bonded atoms.

Question 68

vapor pressure

Answer 68

The pressure exerted by the vapor of a liquid at a given temperature, given its state of dynamic equilibrium between liquid and gas (vapor).

Question 69

viscosity

Answer 69

The resistance of a fluid to flow, and it results from intermolecular attractions that impede the movement of molecules around and past each other.

Question 70

x-ray diffraction analysis

Answer 70

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