Chapter 12 Flashcards
amorphous solid
a solid that has a poorly defined shape because its particles do not have an orderly arrangement throughout a sample
atomic solid
a solid consisting of individual atoms held together by dispersion forces; the frozen noble gases are the only examples
band theory
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
body-centered cubic unit cell
a unit cell in which a particle lies at each corner and in the center of a cube
boiling point
the temperature at which the vapor pressure inside bubbles forming in a liquid equals the external (atmospheric) pressure
branch
a side chain appended to a polymer backbone or to the longest sequence of atoms in an organic compound
capillarity
the rising of a liquid through a narrow space against the pull of gravity
ceramic
a nonmetallic, nonpolymeric solid that is hardened by heating it to high temperatures and, in most cases, consists of silicate microcrystals suspended in a glassy cementing medium
Clausius-clapeyron equation
An equation that expresses the linear relationship between vapor pressure P of a liquid and temperature T;
condensation
the process of a gas changing into a liquid
conduction band
in band theory, the empty, higher energy portion of the band of molecular orbitals into which electrons move when conducting heat and electricity
conductor
a substance (usually a metal) that conducts an electric current well
coordination number
in a crystal, the number of nearest neighbors surrounding a particle. In a complex ion, the number of ligand atoms bonded to the central metal ion
copolymer
a polymer that consists of two or more types of monomer
critical point
the point on a phase diagram above which the vapor cannot be condensed to a liquid; the end of the liquid-gas curve
crosslink
a branch that covalently joins one polymer chain to another
crystal defect
any of a variety of disruptions in the regularity of a crystal structure
crystalline solid
a solid with a well-defined shape because of the orderly arrangement of the atoms, molecules, or ions
cubic closet packing
a crystal structure based on the face-centered cubic unit cell in which the layers have an abcabc . . . pattern
degree of polymerization (n)
the number of repeat units in a polymer chain
deposition
the process of changing directly from a gas to a solid
dipole-dipole force
the intermolecular attraction between oppositely charged poles of nearby polar molecules
dispersion (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 states of nonpolar substances
doping
adding small amounts of other elements into the crystal structure of a semiconductor to enhance a specific property, usually conductivity
elastomer
a polymeric material that can be stretched and springs back to its original shape when released
face-centered cubic unit cell
a unit cell in which a particle occurs at each corner and in the center of each face of a cube
freezing
the process of cooling a liquid until it solidifies
heat of fusion
the enthalpy change occurring when 1 mol of a solid substance melts
heat 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
heat of vaporization
the enthalpy change occurring when 1 mol of a liquid substance vaporizes
heating-cooling curve
a plot of temperature vs. time for a sample when heat is absorbed or released at a constant rate
hexagonal closet packing
a crystal structure based on the hexagonal unit cell in which the layers have an abab . . . pattern
hydrogen 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
insulator
a substance (usually a nonmetal) that does not conduct an electric current
intermolecular forces
the attractive and repulsive forces among the particles—molecules, atoms, or ions—in a sample of matter
ion-dipole force
the intermolecular attractive force between an ion and a polar molecule (dipole)
ionic solid
a solid whose unit cell contains cations and anions
lattice
the three-dimensional arrangement of points created by choosing each point to be at the same location within each particle of a crystal; thus, the lattice consists of all points with identical surroundings
liquid crystal
a substance that flows like a liquid but packs like a crystalline solid at the molecular level
melting (fusion)
the change of a substance from a solid to a liquid
melting point
the temperature at which the solid and liquid forms of a substance are at equilibrium
metallic solid
a solid whose individual atoms are held together by metallic bonding
molecular solid
a solid held together by intermolecular forces between individual molecules
monomer
a small molecule, linked covalently to others of the same or similar type to form a polymer; the repeat unit of the polymer
nanotechnology
the science and engineering of nanoscale systems (size range of 1–100 nm)
network covalent solid
a solid in which all the atoms are bonded covalently so that individual molecules are not present
packing efficiency
the percentage of the total volume occupied by atoms, ions, or molecules in a unit cell
phase
a physically distinct and homogeneous part of a system
phase change
a physical change from one phase to another, usually referring to a change in physical state
phase diagram
a diagram used to describe the stable phases and phase changes of a substance as a function of temperature and pressure
plastic
a material that, when deformed, retains its new shape
polarizability
the ease with which a particle’s electron cloud can be distorted
polymer (macromolecule)
an extremely large molecule that results from the covalent linking of many simpler molecular units (monomers
radius of gyration
a measure of the size of a coiled polymer chain, expressed as the average distance from the center of mass of the chain to its outside edge
random coil
the shape adopted by most polymer chains and caused by random rotation about the bonds joining the repeat units
scanning tunneling microscopy
an instrumental technique that uses electrons moving across a minute gap to observe the topography of a surface on the atomic scale
semiconductor
a substance whose electrical conductivity is poor at room temperature but increases significantly with rising temperature
simple cubic unit cell
a unit cell in which a particle occupies each corner of a cube
sublimation
the process by which a solid changes directly into a gas
superconductivity
the ability to conduct a current with no loss of energy to resistive heating
surface tension
the energy required to increase the surface area of a liquid by a given amount
triple point
the pressure and temperature at which three phases of a substance are in equilibrium. In a phase diagram, the point at which three phase-transition curves meet
unit cell
the smallest portion of a crystal that, if repeated in all three directions, yields the crystal
valence band
in band theory, the lower energy portion of the band of molecular orbitals, which is filled with valence electrons
van der Waals radius
one-half of the closest distance between the nuclei of identical nonbonded atoms
vapor pressure
the pressure exerted by a vapor at equilibrium with its liquid in a closed system
vaporization
the process of changing from a liquid to a gas
viscosity
a measure of the resistance of a fluid to flow
xray diffraction analysis
an instrumental technique used to determine dimensions of a crystal structure by measuring the diffraction patterns caused by x-rays impinging on the crystal
