Chemistry - Ch 11 Flashcards
Condensed phases
Solids & liquids
Intermolecular forces
Forces that exist between molecules
Crystalline
Solids that possess highly ordered 3D structures
Ion-dipole force
Exists between an ion & the partial charge on the end of a polar molecule
Dipole-dipole forces
The force that exists because of the interactions of dipoles on polar molecules in close contact
London dispersion force
Intermolecular forces resulting from attractions between induced dipoles
Polarizability
Measure of the squashiness of its electron cloud; the greater the polarizability of the molecule, the more easily its electron cloud can be distorted to give a momentary dipole
Hydrogen bonding
Special type of intermolecular attraction between the hydrogen atom in a polar bond & non bonding electron pair on a nearby small electronegative ion or atom
Viscosity
Resistance of a liquid to flow
Surface tension
Energy required to increase the surface area of a liquid by a unit amount
Cohesive forces
Intermolecular forces that bind similar molecules to one another (ex. Hydrogen bonding in water)
Adhesive forces
Intermolecular forces that bind a substance to a surface
Capillary action
The rise of liquids up very narrow tubes
Phase changes
Changes of state
Heat of fusion
Enthalpy change for melting a solid
Heat of vaporization
Enthalpy change for vaporization of a liquid
Heat of sublimation
Enthalpy change for vaporization of a solid
Supercooling
Occurs when heat is removed from a liquid so rapidly that the molecules literally have no time to assume the structure of a solid
Critical temperature
Highest temp at which a distinct liquid phase can form
Critical pressure
Pressure required to bring about liquefaction at critical temp
Vapor pressure
Pressure exerted by a vapor in equilibrium with its liquid or solid phase
Dynamic equilibrium (equilibrium)
Condition in which 2 opposing processes are occurring simultaneously at equal rates
Volatile
Liquids that evaporate readily
Normal boiling point
Boiling point of a liquid at 1atm (760 torr) pressure
Phase diagram
Graphic way to summarize the conditions under which equilibria exist between the different states of matter
Normal melting point
Melting point at 1 atm
Triple point
Point on a phase diagram where all 3 phases are in equilibrium at this temp & pressure (points intersect)
Crystalline solid
Atoms, ions, or molecules are ordered in well-defined 3d arrangements
Amorphous solid
Solid in which particles have no orderly structure
Unit cell
Repeating unit of a solid, the crystalline “brick”
Crystal lattice
3D array of points of a crystalline solid
Primitive cubic
When lattice points are at corners only
Body-centered cubic
When a lattice point also occurs at the center of the unit cell
Face-centered cubic
When the cell has lattice points at the center of each face as well as at each corner
Hexagonal close packing
Arrangement in which the atoms of the 3rd layer of a solid lie directly over those in the 1st layer
Cubic close packing
Arrangement in which the atoms of the 3rd layer of a solid are not directly over those in the 1st layer
Coordination number
Number of particles immediately surrounding a particle in the crystal structure
Molecular solids
Atoms or molecules held together by intermolecular forces (dipole-dipole forces, London dispersion forces, and hydrogen bonds)
Covalent network solids
Atoms held together throughout the entire sample of material in large networks or chains by covalent bonds
Ionic solids
Ions held together by ionic bonds
Metallic solids (metals)
Consist entirely of metal atoms; usually have hexagonal close-packed, cubic close-packed (face-centered cubic), or body-centered cubic structures
