Chemistry - Chapter 12 Vocab

Front 1

phase

Back 1

a physically distinct portion of a system

Front 2

intermolecular forces

Back 2

the attractive and repulsive forces among the particles -molecules, atoms, or ions - in a sample of matter

Front 3

phase change

Back 3

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

Front 4

condensation

Back 4

the process of a gas changing into a liquid

Front 5

vaporization

Back 5

the process of changing from a liquid to a gas

Front 6

freezing

Back 6

the process of cooling a liquid until it solidifies

Front 7

melting
(fusion)

Back 7

the change of a substance from a solid to a liquid

Front 8

heat of vaporization

Back 8

the enthalpy change occuring when 1 mol of a liquid substance vaportizes

Front 9

heat of fusion

Back 9

the enthalpy change occurring when 1 mol of a solid substance melts

Front 10

sublimation

Back 10

the process by which a solid changes directly into a gas

Front 11

deposition

Back 11

the process of changing directily from gas to solid

Front 12

heat of sublimation

Back 12

the enthalpy change occurring when 1mol of a substance changes directly to a gas. the sum of the heats of fusion and vaporization

Front 13

heating-cooling curve

Back 13

a plot of temperature vs. time for a substance when heat is absorbed or released by the system at a constant rate

Front 14

dynamic equilibrium

Back 14

in a chemical or physical change, the condition at which the forward and reverse processes take place at the same rate, so there is no net charge in the amounts of reactants or products

Front 15

vapor pressure

Back 15

the pressure exerted by a vapor at equilibrium when its liquid is in a closed system

Front 16

clausius-clapeyon equation

Back 16

an equation that expresses the relationship between vapor pressure P of a liquid and temperature T

Front 17

boiling point

Back 17

the temperature at which the vapor pressure of a gas equals the external (atmospheric) pressure

Front 18

melting point

Back 18

the temperature atg which the solid and liquid forms of a substance are at equilibrium

Front 19

phase diagram

Back 19

a diagram used to describe the stable phase and phase changes of a substance as a function of temperature and pressure

Front 20

critical point

Back 20

the point on a phase diagram above which the vapor cannot be condensed to a liquid; the end of the liquid-gas curve

Front 21

triple point

Back 21

the pressure and temperature at which the three phases of a substance are in equilibrium. in a phase diagram, the point at which the three phase-transition curves meet

Front 22

Vand der Waals radius

Back 22

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

Front 23

ion-dipole force

Back 23

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

Front 24

hydrogen bond

Back 24

(H bond)

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

Front 25

dispersion (london) force

Back 25

the intermolecular attraction between all particles as a result of instantaneous polarizations of their electron clouds; the intermolecular force primarily responsible for the condensed states of nonpolar substances

Front 26

surface tension

Back 26

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

Front 27

capillarity

Back 27

(capillary action)

a property that results in a liquid rising through a narrow space against gravity

Front 28

viscosity

Back 28

a measure of the resistance of a liquid to flow

Front 29

crystalline solid

Back 29

solid with a well defined shape because of the orderly arrangement ofthe atoms, molecules, or ions

Front 30

amorphous solid

Back 30

a solid that occurs in different shapes because it lacks extensive molecular-level ordering of its particles

Front 31

lattice

Back 31

the three-dimensional arrangement of points created by choosing each point to be at the same location within each particle or a crystal; thus, the lattice consists of all points with identical surroundings

Front 32

unti cell

Back 32

the smallest portion of a crystal that, if repeated in all three directions, gives the crystal

Front 33

coordination number

Back 33

in a crystal, the number of nearest neighbors surrounding a particle

Front 34

simple cubic unit cell

Back 34

a unit cell in which a partcile occurs at each corner of a cube

Front 35

body-centered cubic unit cell

Back 35

a unit cell in which a particle lies at each corner and in the center of the cube

Front 36

face-centered cubic unit cell

Back 36

a unit cell in which a particle occurs at each corner and in the center of each face of a cube

Front 37

packing efficiency

Back 37

the percentage of the available volume occupied by atoms, ions or molecules in a unit cell

Front 38

hexagonal closet packing

Back 38

a crystal structure based on the hexagonal unit cell in which the layers have an abab.. pattern

Front 39

cubic closet packing

Back 39

a crystal structure based on the face-centered cubic unit cell in which the layers have an abcabc... pattern

Front 40

x-ray diffraction analysis

Back 40

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

Front 41

atomic solid

Back 41

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

Front 42

molecular solid

Back 42

a solid held together by intermolecular forces between individual molecules

Front 43

ionic solid

Back 43

a solid whose unit cell contains cations and anions

Front 44

metallic solid

Back 44

a solid whos individual atoms are held together by metallic bonding

Front 45

network covalent solid

Back 45

a solid in which all the atoms are bonded covalently

Front 46

electron-sea model

Back 46

a qualitative description of metallic bonding proposing that metal atoms pool their valence electrons into a delocalized "sea" of electrons in which the metal cores (metal ions) are submerged in an orderly array

Front 47

band theory

Back 47

an extension of molecular orbital (MO) theory that explains many properties of metals, in particular, the differences in electrical condiuctivity of conductors, semiconductors, and insulators

Front 48

valence band

Back 48

in band theory, the lower energy portion of the band of mnolecular orbitals, which is filled with valence electrons

Front 49

conduction band

Back 49

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

Front 50

conductor

Back 50

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

Front 51

semi conductor

Back 51

a substance whose electrical conductivity is poor at room temperature but increases significatnly with rising temperature

Front 52

insulator

Back 52

a substance (usually a nonmetal) that does not condeuct an electric current

Front 53

superconductivity

Back 53

the ability to conduct a current with no loss of energy to resitive heating