Chapter 12 Vocab

Question 1

Phase

Answer 1

A physically distinct and homogeneous part of a system.

Question 2

Intermolecular forces

Answer 2

(Also interparticle forces) The attractive and repulsive forces among the particles - molecules, atoms, or ions - in a sample of matter.

Question 3

Phase change

Answer 3

A physical change from one phase to another, usually referring to a change in physical state.

Question 4

Melting

Answer 4

(Also fusion) the change of a substance from a solid to a liquid.

Question 5

Heat of fusion (ΔH°fus)

Answer 5

(Also enthalpy of fusion) The enthalpy change occurring when 1 mol of a solid substance melts; designated ΔH°fus at the standard state.

Question 6

Freezing

Answer 6

The process of cooling a liquid until it solidifies.

Question 7

Vaporization

Answer 7

The process of changing from a liquid to a gas.

Question 8

Heat of vaporization

Answer 8

(Also enthalpy of vaporization) The enthalpy change occurring when 1 mol of a liquid substance vaporizes; designated ΔH°vap at the standard state.

Question 9

Condensation

Answer 9

The process of a gas changing into a liquid.

Question 10

Sublimation

Answer 10

The process by which a solid changes directly into a gas.

Question 11

Heat of sublimation

Answer 11

(Also enthalpy of sublimation) The enthalpy change occurring when 1 mol of a solid substance changes directly to a gas. The sum of the heats of fusion and vaporization; designed ΔH°subl at the standard state.

Question 12

Deposition

Answer 12

The process of changing directly from a gas to a solid.

Question 13

Heating-cooling curve

Answer 13

A plot of temperature vs. time for a sample when heat is absorbed or released at a constant rate.

Question 14

Vapor pressure

Answer 14

(Also equilibrium vapor pressure) The pressure exerted by a vapor at equilibrium with its liquid in a closed system.

Question 15

van der Waals radius

Answer 15

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

Question 16

Ion-dipole force

Answer 16

The intermolecular attractive force between an ion and a polar molecule (dipole).

Question 17

Dipole-dipole force

Answer 17

The intermolecular attraction between oppositely charged poles of nearby polar molecules.

Question 18

Hydrogen bond (H bond)

Answer 18

A type of dipole-dipole force that arises between molecules that have an H atom bonded to a small, highly electronegative atom with lone pairs, usually N, O, or F.

Question 19

Polarizability

Answer 19

The ease with which a particle’s electron cloud can be distorted.

Question 20

Dispersion force

Answer 20

(Also London force) The intermolecular attraction between all particles as a result of instantaneous polarizations of their electron clouds; the intermolecular force primarily responsible for the condensed state of nonpolar substances.

Question 21

Surface tension

Answer 21

The energy required to increase the surface area of a liquid by a given amount.

Question 22

Capillarity

Answer 22

(Also capillary action) The rising of a liquid through a narrow space against the pull of gravity.

Question 23

Viscosity

Answer 23

A measure of the resistance of a fluid to flow.

Question 24

X-ray diffraction analysis

Answer 24

An instrumental technique used to determine dimensions of a crystal structure by measuring the diffraction patterns caused by x-rays impinging on the crystal.

Question 25

Scanning tunneling microscopy

Answer 25

An instrumental technique that uses electrons moving across a minute gap to observe the topography of a surface on the atomic scale.

Question 26

Atomic solid

Answer 26

A solid consisting of individual atoms held together by dispersion forces; the frozen noble gases are the only examples.

Question 27

Molecular solid

Answer 27

A solid held together by intermolecular forces between individual molecules.

Question 28

Ionic solid

Answer 28

A solid whose unit cell contains cations and anions.

Question 29

Metallic solid

Answer 29

A solid whose individual atoms are held together by metallic bonding.

Question 30

Network covalent solid

Answer 30

A solid in which all the atoms are bonded covalently so that individual molecules are not present.

Question 31

Band theory

Answer 31

An extension of molecular orbital (MO) theory that explains many properties of metals and other solids - in particular, the differences in conductivity of metals, metalloids, and nonmetals.

Question 32

Valence band

Answer 32

In band theory, the lower energy portion of the band of molecular orbitals, which is filled with valence electrons.

Question 33

Conduction band

Answer 33

In band theory, the empty, higher energy portion of the band of molecular orbitals into which electrons move when conducting heat and electricity.

Question 34

Conductor

Answer 34

A substance (usually a metal) that conducts an electric current well.

Question 35

Semiconductor

Answer 35

A substance whose electrical conductivity is poor at room temperature but increases significantly with rising temperature.

Question 36

Insulator

Answer 36

A substance (usually a nonmetal) that does not conduct an electric current.

Question 37

Superconductivity

Answer 37

The ability to conduct a current with no loss of energy to resistive heating.

Question 38

Crystal defect

Answer 38

Any of a variety of disruptions in the regularity of a crystal structure.

Question 39

Doping

Answer 39

Adding small amounts of other elements into the crystal structure of a semiconductor to enhance a specific property, usually conductivity.

Question 40

Liquid crystal

Answer 40

A substance that flows like a liquid but packs like a crystalline solids t the molecular level.

Question 41

Ceramic

Answer 41

A nonmetallic, nonpolymeric solid that is hardened by heating it to high temperatures an, in most case, consists of silicate microcrystals suspended in a glassy cementing medium.

Question 42

Polymer

Answer 42

(Also macromolecule) An extremely large molecule that results from the covalent linking of many simpler molecular units (monomers).

Question 43

Monomer

Answer 43

A small molecule, linked covalently to others of the same or similar type to form a polymer; the repeat unit of the polymer.

Question 44

Degree of polymerization (n)

Answer 44

The number of repeat units in a polymer chain.

Question 45

Random coil

Answer 45

The shape adopted by most polymer chains and caused by random rotation about the bonds joining the repeat units.

Question 46

Radius of gyration (Rg)

Answer 46

A measure of the size of a coiled polymer chain, expressed as the average distance from the center of mass to the chain to its outside edge.

Question 47

Plastic

Answer 47

A material that, when deformed, retains its new shape.

Question 48

Branch

Answer 48

A side chain appended to a polymer backbone or to the longest sequence of atoms in an organic compound.

Question 49

Crosslink

Answer 49

A branch that covalently joins one polymer chain to another.

Question 50

Elastomer

Answer 50

A polymeric material that can be stretched and springs back to its original shape when released.

Question 51

Copolymer

Answer 51

A polymer that consists of two or ore types of monomer.

Question 52

Nanotechnology

Answer 52

The science and engineering of nanoscale systems (size range of 1-100 nm).