AP Chemistry Unit 5 - Chapter 10

Condensed states

liquids and solids

intermolecular forces

forces of attraction between molecules

dipole-dipole attraction

intermolecular attraction between two permanent dipoles

Hydrogen bonding

intermolecular force in which a H atom that is bonded to a highly electronegative atom (N, O, F) is attracted to an unshared pair of electrons of an electronegative atom (N, O, F) in a nearby molecule

London Dispersion Forces (LDF)

The intermolecular attractions resulting from the constant motion of electrons distorting nearby electron clouds and creating temporary dipoles. (Always attractive)

Surface tension

The resistance of a liquid to an increase in its surface area -Direct relationship

capillary action

spontaneous rising of a liquid through a narrow tube against the force of gravity (Cohesive - attarcts to itself, Adhesive - Attracts to other substance) -Direct relationship

Viscosity

A liquid's resistance to flowing (thickness) -Direct relationship -increases with molecular complexity

crystalline solid

A solid that is made up of crystals in which particles are arranged in a regular, repeating pattern

Amorphus solid

A solid made up of particles that are not arranged in a regular pattern

Lattice

3D system of points designating the positions of the centers of the components of a solid

Unit cell

the smallest repeating unit of a lattice

X-ray diffraction

an analytical method in which X-rays change direction on contact with matter, resulting in changes in radiation intensity, that is used to determine the three-dimensional arrangement of atoms.

ionic solid

A solid consisting of ions at the points of the lattice

molecular solid

a solid composed of covalently bonded molecules at the lattice points

atomic solid

a solid that contains atoms at the lattice points

Band model (Molecular orbital (MO) model)

a molecular model for metals in which the electrons are assumed to travel around the metal crystal in molecular orbitals formed from the valence atomic orbitals of the metal atoms

Alloy

a combination; a mixture of two or more metals

substitutional alloy

some of the host metal atoms are replaced by other metal atoms of similar sizes

interstitial alloy

a mixture formed when small atoms fill holes in a metallic crystal

Network solid

atomic solids containing strong directional covalent bonds to form a solid that might best be viewed as a "giant molecule."

Silica

the fundamental silicon-oxygen compound, which has the empirical formula SiO2, and forms the basis of quartz and certain types of sand

Glass

An amorphous solid obtained when silica is heated above its melting point (1600°C) and cooled rapidly

semiconductor

A substance that can conduct electricity under some conditions

Insulator

A material that does not allow heat or electrons to move through it easily.

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 semiconductor

a semiconductor that employs positively charged "holes" in the valence band as the charge carriers

p-n junction

a connection between a p-type semiconductor and an n-type semiconductor

vaporization (evaporation)

the change in state that occurs when a liquid becomes a gas _____________ (boiling) occurs when the vapor pressure of the liquid is equal to the pressure of the atmosphere

enthalpy of vaporization (ΔHvap) or heat of vaporization

The energy required to vaporize 1 mole of a liquid at a pressure of 1 atm

Condensation

The change of state from a gas to a liquid

Equilibrium

a state in which opposing forces or influences are balanced.

vapor pressure

the pressure of the vapor present at equilibrium

Sublimation

A change directly from the solid to the gaseous state without becoming liquid

Heating curve

a plot of temperature versus time for a substance where energy is added at a constant rate

enthalpy (heat) of fusion (ΔHfus)

The enthalpy change that occurs at the melting point when a solid melts

Normal melting point

the temperature at which the solid and liquid states have the same vapor pressure under conditions where the total pressure is 1 atmosphere

Normal boiling point

the temperature at which the vapor pressure of a liquid is exactly 1 atm

Supercooled

the process of cooling a liquid below its freezing point without its changing to a solid

Superheated

the process of heating a liquid above its boiling point without it boiling

Phase diagram

A graph of pressure versus temperature that shows the conditions under which the phases of a substance exist

Triple point

the temperature and pressure conditions at which the solid, liquid, and gaseous phases of a substance coexist at equilibrium

Critical temperature

the temperature above which a substance cannot exist in the liquid state

Critical pressure

the lowest pressure at which a substance can exist as a liquid at the critical temperature

Critical point

the temperature and pressure at which the gas and liquid states of a substance become identical and form one phase

Types of Van der Waals interactions

LDF’s, dipole-induced dipole, dipole-dipole, H-bonds, Ion-dipole

Stronger intermolecular forces creates ____________

Higher melting and boiling points, as well as higher enthalpies of fusion and vaporization

Strength of LDFs depends on..,

Polarizability of the electron cloud and the shape of the molecule When a molecules surface area is higher, there is greater opportunity for induced dipoles

dipole-induced dipole

The partial charge on a polar molecule induces a temporary partial charge on a neighboring nonpolar molecule or atom (Always attractive)

London dispersion forces Dipole-induced dipole Dipole-dipole H-bonds Ion-dipole forces

Relative strengths of all intermolecular forces

ion-dipole forces

attractive forces between an ion and a polar molecule

the pressure of a vapor in equilibrium with its liquid or solid form Stronger _____ result in lower ________ ___________

IMFs

Vapor pressure

Vaporization @ boiling point Vaporization below boiling point

boiling evaporation

Volatility

a measure of how readily a substance vaporizes -Inverse relationship

Miscible

Describes two liquids that are soluble in each other