- adhesive force
- force of attraction between molecules of different chemical identities
- amorphous solid
- (also, noncrystalline solid) solid in which the particles lack an ordered internal structure
- body-centered cubic (BCC) solid
- crystalline structure that has a cubic unit cell with lattice points at the corners and in the center of the cell
- body-centered cubic unit cell
- simplest repeating unit of a body-centered cubic crystal; it is a cube containing lattice points at each corner and in the center of the cube
- boiling point
- temperature at which the vapor pressure of a liquid equals the pressure of the gas above it
- Bragg equation
- equation that relates the angles at which X-rays are diffracted by the atoms within a crystal
- capillary action
- flow of liquid within a porous material due to the attraction of the liquid molecules to the surface of the material and to other liquid molecules
- Clausius-Clapeyron equation
- mathematical relationship between the temperature, vapor pressure, and enthalpy of vaporization for a substance
- cohesive force
- force of attraction between identical molecules
- condensation
- change from a gaseous to a liquid state
- coordination number
- number of atoms closest to any given atom in a crystal or to the central metal atom in a complex
- covalent network solid
- solid whose particles are held together by covalent bonds
- critical point
- temperature and pressure above which a gas cannot be condensed into a liquid
- crystalline solid
- solid in which the particles are arranged in a definite repeating pattern
- cubic closest packing (CCP)
- crystalline structure in which planes of closely packed atoms or ions are stacked as a series of three alternating layers of different relative orientations (ABC)
- deposition
- change from a gaseous state directly to a solid state
- diffraction
- redirection of electromagnetic radiation that occurs when it encounters a physical barrier of appropriate dimensions
- dipole-dipole attraction
- intermolecular attraction between two permanent dipoles
- dispersion force
- (also, London dispersion force) attraction between two rapidly fluctuating, temporary dipoles; significant only when particles are very close together
- dynamic equilibrium
- state of a system in which reciprocal processes are occurring at equal rates
- face-centered cubic (FCC) solid
- crystalline structure consisting of a cubic unit cell with lattice points on the corners and in the center of each face
- face-centered cubic unit cell
- simplest repeating unit of a face-centered cubic crystal; it is a cube containing lattice points at each corner and in the center of each face
- freezing
- change from a liquid state to a solid state
- freezing point
- temperature at which the solid and liquid phases of a substance are in equilibrium; see also melting point
- hexagonal closest packing (HCP)
- crystalline structure in which close packed layers of atoms or ions are stacked as a series of two alternating layers of different relative orientations (AB)
- hole
- (also, interstice) space between atoms within a crystal
- hydrogen bonding
- occurs when exceptionally strong dipoles attract; bonding that exists when hydrogen is bonded to one of the three most electronegative elements: F, O, or N
- induced dipole
- temporary dipole formed when the electrons of an atom or molecule are distorted by the instantaneous dipole of a neighboring atom or molecule
- instantaneous dipole
- temporary dipole that occurs for a brief moment in time when the electrons of an atom or molecule are distributed asymmetrically
- intermolecular force
- noncovalent attractive force between atoms, molecules, and/or ions
- interstitial sites
- spaces between the regular particle positions in any array of atoms or ions
- ionic solid
- solid composed of positive and negative ions held together by strong electrostatic attractions
- isomorphous
- possessing the same crystalline structure
- melting
- change from a solid state to a liquid state
- melting point
- temperature at which the solid and liquid phases of a substance are in equilibrium; see also freezing point
- metallic solid
- solid composed of metal atoms
- molecular solid
- solid composed of neutral molecules held together by intermolecular forces of attraction
- normal boiling point
- temperature at which a liquid’s vapor pressure equals 1 atm (760 torr)
- octahedral hole
- open space in a crystal at the center of six particles located at the corners of an octahedron
- phase diagram
- pressure-temperature graph summarizing conditions under which the phases of a substance can exist
- polarizability
- measure of the ability of a charge to distort a molecule’s charge distribution (electron cloud)
- simple cubic structure
- crystalline structure with a cubic unit cell with lattice points only at the corners
- simple cubic unit cell
- (also, primitive cubic unit cell) unit cell in the simple cubic structure
- space lattice
- all points within a crystal that have identical environments
- sublimation
- change from solid state directly to gaseous state
- supercritical fluid
- substance at a temperature and pressure higher than its critical point; exhibits properties intermediate between those of gaseous and liquid states
- surface tension
- energy required to increase the area, or length, of a liquid surface by a given amount
- tetrahedral hole
- tetrahedral space formed by four atoms or ions in a crystal
- triple point
- temperature and pressure at which the vapor, liquid, and solid phases of a substance are in equilibrium
- unit cell
- smallest portion of a space lattice that is repeated in three dimensions to form the entire lattice
- vacancy
- defect that occurs when a position that should contain an atom or ion is vacant
- van der Waals force
- attractive or repulsive force between molecules, including dipole-dipole, dipole-induced dipole, and London dispersion forces; does not include forces due to covalent or ionic bonding, or the attraction between ions and molecules
- vapor pressure
- (also, equilibrium vapor pressure) pressure exerted by a vapor in equilibrium with a solid or a liquid at a given temperature
- vaporization
- change from liquid state to gaseous state
- viscosity
- measure of a liquid’s resistance to flow
- X-ray crystallography
- experimental technique for determining distances between atoms in a crystal by measuring the angles at which X-rays are diffracted when passing through the crystal