ch 10 liquids and solids

van der Waals forces

attractive or repulsive force between molecules

London dispersion forces

b/c the electrons of an atom are constantly moving, it can develop a temporary, instantaneous dipole if its electrons are distributed asymmetrically

induced dipole

the presence of London dispersion forces can distort the electrons of a neighboring atom, producing an ____ ____.

stronger

Larger atoms exhibit ____ dispersion forces.

Larger

____ atoms form more temporary dipoles b/c their electrons are less tightly held; have higher boiling points.

dipole-dipole attraction

the electrostatic force between the partially positive end of one polar molecule and the partially negative end of another

hydrogen bonding

occurs when exceptionally strong dipoles attract; hydrogen bonds to one of the three most electronegative elements (F, O, N)

viscosity

measure of a liquid’s resistance to flow (mPa s)

cohesive forces

forces of attraction between IDENTICAL molecules

surface tension

the energy required to increase the surface area of a liquid (mN/m)

adhesive forces

the IMFs of attraction between two DIFFERENT molecules

capillary action

when a liquid flows within a porous material due to the attraction of the liquid molecules to the surface of the material and to other liquid molecules

condensation

change from gas to liquid (molecules condense)

equilibrium

when the rates of condensation and vaporization are equal, the states will not change b/c they are in ____.

dynamic equilibrium

reciprocal processes occur at equilibrium

vapor pressure

pressure exerted by a vapor in equilibrium with a liquid

boiling point

temperature at which a liquid’s equilibrium vapor pressure equals the external pressure from its gaseous surroundings

normal boiling point

boiling point when surrounding pressure is equal to 1 atm

Clausius-Clapeyron equation

ln(P₂/P₁) = ((ΔH_vap)/R) (1/T₁ - 1/T₂)

q

_ = mcΔT

triple point

at the ____ ____, the three phases exist in equilibrium.

supercritical

when a substance is at a temperature and pressure higher than its critical point, it is a ____ fluid. these substances exist in a state between liquid and gas.

critical temperature

above the ____ ____, a gas cannot be liquefied no matter how much pressure is applied.

critical pressure

pressure needed to liquefy a gas at its critical temperature

crystalline

in ____ solids, the atoms are arranged in a definite repeating pattern.

amorphous

in ____ solids, the atoms are randomly arranged (the liquid froze before they could arrange).

crystalline

metals and ionic compounds often form ____ solids.

amorphous

substances with large molecules or a mixture of molecules with restricted movement often form ____ solids.

ionic solids

positive and negative ions held together by electrostatic attractions; have high melting points

ionic

many simple metal-nonmetal compounds are ____.

metallic solids

crystals of copper, aluminum, iron, etc.; atoms are held together by metallic bonding; high thermal and electric conductivity

covalent network solids

crystals of diamond, silicon, etc; atoms are held together by a network of covalent bonds; hard and strong with high melting points

molecular solid

ice, sucrose (sugar), iodine, etc.; composed of neutral molecules; strength of IMFs vary widely

vacancy

a crystal defect that occurs when positions that should contain atoms are vacant

intersitial site

in this crystal defect, sometimes atoms occupy an ____ ____ between regular positions for atoms.

pure metal

a ____ ____ is a crystalline solid with metal atoms packed closely together in a repeating pattern.

sizes

the properties of specific atoms depend on the ____ of their atoms.

unit cell

smallest portion of a space lattice that is repeated in three dimensions to form the entire lattice; consists of points that represent the locations of atoms or ions

coordination number

number of other particles that each particle in a crystalline solid contacts

6

simple cubic arrays have a coordination number of ___.

8

a body-centered cubic array has a coordination number of ___.

12

a face-centered cubic array has a coordination number of ___.

ionic crystals

____ ____ consist of two or more kinds of ions, usually with different sizes.

cubic structures

ionic compounds crystallize with ____ ____.

simple cubic structure

when an ionic compound has cations and anions of similar size in a 1:1 ratio, it typically forms a ____ ____ ____.

space lattice

all points within a crystal that have identical environments

diffraction

change in direction of travel experienced by an electromagnetic wave when it encounters a physical barrier with comparable dimensions to the light’s wavelength

diffraction

size of a unit cell and arrangement of atoms in a crystal may be determined from measuring the ____ of x-rays of the crystal.

interference

when parallel scattered waves combine to yield either an increase or decrease in amplitude

bragg equation

nλ = 2dsinθ