condensed states
matters such as liquids and solids that are tightly bound and condensed with covalent or ionic bonding
intermolecular forces
weaker interactions that occur between, rather within, the actual molecule
dipole-dipole attraction
the attractive force resulting when polar molecules line up so that the positive and negative ends touch
hydrogen bonding
strong dipole-dipole attractions that occur among molecules in which hydrogen is bonded to a highly electronegative atom
London dispersion forces
the forces existing among noble gas atoms and nonpolar molecules, that involve an accidental dipole that introduces a momentary dipole in a neighbor
surface tension
the resistance of a liquid to an increase in surface area
capillary action
the spontaneous rising of a liquid in a narrow tube
viscosity
the resistance of a liquid to flow
crystalline solid
a solid with a regular arrangement of its components
amorphous solid
a solid with a considerate disorder in its structure
lattice
a three dimensional system of points designating the positions of the centers of the components of a sold (atoms, ions, molecules)
unit cell
the smallest repeating unit of a lattice
X-Ray diffraction
a technique for establishing the structure of a crystalline solid by directing X Rays of a single wave length at a crystal and obtaining a diffraction patter from which interatomic spaces can be seen
ionic solid (salt)
solid containing cations and anions that dissolves in water to give a solution containing the separated ions which are mobile and free to conduct current
molecular solid
solid composed of neutral molecules in the lattice points
atomic solid
a solid that contains atoms at the lattice points
closet packing
an arrangement in which uniform, hard spheres are packed in a manner that most efficient uses available space
hexagonal closet packed (hcp) structure
a closed packed structure with an ababab arrangement of layers; the unit cell is hexagonal
cubic closest packed (ccp) structure
a closet packed structure with an abcabc arrangement of layers; the unit cell is face-centered cubic
band model
a molecular model for metals in which the electrons are assumed to travel around the metal crystal in molecular orbitals formed from valence atomic orbitals of the metal atoms
molecular orbital (mo) model
a model that regards a molecule as a connection of nuclei and electrons, where the electrons are assumed to occupy orbitals as they do in atoms, but have the atoms extend over the molecule. Electrons are always delocalized.
alloy
a substance that contains a mixture of elements and has metallic properties
substitutional alloy
an alloy in which some of the host metal atoms are replaced by other atoms of a similar size
interstitial alloy
formed when some of the interstices in the closet packed metals structure are occupied by small atoms
network solids
an atomic solid containing strong directional covalent bonds
silica
the fundamental silicon-oxygen compound, which has the empirical formula SiO2 and forms the basis of quarts and some sands
silicate
salts that contain metal cations and polyatomic silicon-oxygen snions that are usually polymeric
glass
an amorphous solid obtained when silica is mixed with other compounds, headed above its melting point, and then cooled rapidly
ceramic
nonmetallic metal made from clay and hardened by firing at high temperature it contains minute silicate crystals suspended in glassy cement
semiconductor
substance containing only a slight electrical current at room temperature, but showing increased conductivity at higher temperatures
n-type semiconductor
a substance whose conductivity is increased by doping it with atoms having more valence electrons than the atoms in the host crystal
p-type semiconductors
semiconductors doped with atoms having fewer valence electrons than the atoms of the host crystal
p-n junction
a p and n crossing where a small number of electrons migrate from the n-type region to the p-type region
vaporization (evaporation)
the change in state that occurs when a liquid evaporates to form a gas
heat of vaporization
the energy required to vaporize one more of a liquid at a pressure of one atmosphere
enthalpy of vaporization (Hvap)
the energy required to vaporize one mole of a liquid at a pressure of one atmosphere (H)
condensation
the process by which vapor molecules reform a liquid
equilibrium
the point in the system where there is no further net change that occurs in the amount of liquid or vapor because the two opposite processes exactly balance each other
equilibrium vapor pressure
the pressure of the vapor present at equilibrium with its condensed phases in a closed system
sublimation
the process by which a substances goes directly from the solid to the gaseous sate without passing through the liquid state
heating curve
the plot of temperature versus time for a substance where energy is added at a constant rate
enthalpy (heat) of fusion (Hfux)
the enthalpy change that occurs to melt a solid at its melting point
normal melting point
the temperature at which the solid and liquid state have the same vapor pressure under conditions where the total pressure on the system is one atmosphere
normal boiling point
the temperature at which the vapor pressure of a liquid is exactly one atmosphere
supercooled
a liquid is cooled below its freezing points without changing to a solid
superheated
a liquid is heated above its boiling point without change to a gas