Book: Key Terms: 12 Flashcards
amorphous solid
Have poorly defined shapes because their particles do not have an orderly arrangement throughout a sample.
atomic solid
Individual atoms held together only by dispersion forces. Noble gases are the only substances that form such solids.
band theory
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.
body-centered cubic unit cell
Identical particles lie at each corner and in the center of the cube. Coordination number is 8.
boiling point
The temperature at which the vapor pressure inside the bubbles in the liquid equals the external pressure.
branch
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capillarity
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).
Clausius-Clapeyron equation
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)
condensation
As temperature drops, molecules in the gas phase come together and form a liquid.
conduction band
*
conductor
*
coordination number
A parameter of any lattice. It is the number of nearest neighbors of a particle in a crystal.
copolymer
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critical point
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.
crosslink
*
crystal defect
*
crystalline solid
have well-defined shapes because their particles—atoms, molecules, or ions—occur in an orderly arrangement.
cubic closest packing
An arrangement based on the face-centered cubic unit cell which is the most efficient packing of particles in the cubic lattice.
degree of polymerization
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deposition
Phase change of a gas directly into a solid.
dipole-dipole forces
A type of intermolecular force arising due to the electric field produced by polar molecules arranging the atoms and pulling them together.
dispersion (London) forces
An intermolecular force present in all particles which results from the movement of electrons.
doping
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elastomer
*
face-centered cubic unit cell
Identical particles lie at each corner and in the center of each face but not the center of the cube. Coordination number is 12.
freezing
As temperature drops, particles in a liquid move more slowly and become fixed in position, forming a solid.
fusion
Phase change from a solid to a liquid—essentially melting.
heat of fusion
The standard enthalpy change associated with a phase change between a solid and a liquid.
heat of sublimation
The standard enthalpy change associated with a phase change between a solid and a gas.
heat of vaporization
The standard enthalpy change associated with a phase change between a gas and a liquid.
heating-cooling curve
Shows the changes in temperature of a sample when heat is absorbed or released at a constant rate.
hexagonal closest packing
*
hydrogen bond (H bond)
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.
insulator
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intermolecular forces
A form of potential energy that tends to draw molecules together.
ion-dipole force
When an ion and a nearby polar molecule (dipole) attrach each other.
ionic solid
binary ionic compounds form ionic solids, which are lattices.
lattice
a collection of points which form a regular pattern
liquid crystal
*
London force
dispersion forces.
macromolecule
*
melting point
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.
melting (fusion)
fusion
metallic solid
Powerful metallic bonding forces fix metallic elements into crystals called metallic solids.
molecular solid
A crystalline structure in which molecules occupy the lattice points.
monomer
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nanotechnology
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network covalent solid
Strong covalent bonds link the atoms together and separate particles are not present in these.
packing efficiency
The percentage of the total volume of the unit cell occupied by the spheres (atoms) themselves.
phase
A physically distinct, homogeneous part of a system.
phase change
liquid to solid, solid to gas, etc.
phase diagram
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.
plastic
*
polarizability
A measure of how easily the electron cloud of an atom (or ion) can be distorted.
polymer
*
radius of gyration
*
random coil
*
scanning tunneling microscopy
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semiconductor
*
simple cubic unit cell
The centers of eight identical particles occupy the corners of a cube.
sublimation
The direct phase change from a solid to a gas.
superconductivity
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surface tension
The energy required to increase the surface area by a given amount and has units of J/m^2
triple point
the point of intersection on a phase diagram between the three phase-transition curves.
unit cell
The smallest portion of a crystal that yields the crystal if it is repeated in all directions.
valence band
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van der Waals radius
one-half the closest distance between the nuclei of identical, non-bonded atoms.
vapor pressure
The pressure exerted by the vapor of a liquid at a given temperature, given its state of dynamic equilibrium between liquid and gas (vapor).
viscosity
The resistance of a fluid to flow, and it results from intermolecular attractions that impede the movement of molecules around and past each other.
x-ray diffraction analysis
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