Gen Chem 2: Exam 1(Ch10 & 11)

INTRAmolecular forces

INTRAmolecular forces

attractions within the molecule that keep the molecule together, like the bonds between the atoms

INTERmolecular forces

attractions between molecules, which determine many of the physical properties of a substance, like boiling point

dispersion forces

temporary polarity in the molecules due to unequal electron distribution

• present in ALL molecules and atoms

dipole-dipole attractions

permanent polarity in the molecules due to their structure leads to attractive forces

• present in POLAR molecules

hydrogen bonds

especially strong dipole-dipole attraction that results when Hydrogen is attached to an extremely electronegative atom

• H-N

• H-O

• H-F

Nonpolar molecules ONLY have

london dispersion force

the stronger the IMFs

the higher the boiling point and melting point

the more surface-to-surface contact in the shape of a molecule

the stronger the IMFs, the higher the boiling and melting point

ion-dipole

mixture of ionic compound and polar molecules

viscosity

the resistance of a liquid to flow

• the stronger the IMFs, the higher the viscosity will be

• the less contact surface the molecule as, the lower the viscosity will be

• increase the temperature of a liquid will reduce its viscosity

surface tension

energy required to increase the surface area of a liquid, the force required to increase the length of a liquid surface by a given amount

• the stronger the IMFs, the higher the surface tension

• increase the temperature of a liquid reduces its surface tension

cohesive force

the IMFs between identical molecules of a substance

adhesive force

the IMFs between two different molecules

• ex: water on a leaf

capillary action

The adhesive forces between the liquid and the porous material, combined with the cohesive forces within the liquid, may be strong enough to move the liquid upward against gravity

• the narrower the tube, the higher the liquid rises

meniscus

the curving of the liquid surface in a thin tube due to the competition between cohesive and adhesive forces

concave meniscus

water’s adhesion to the glass is stronger than its cohesion for itself

• water is attracted to the glass more than other water molecules

convex

mercury’s cohesion for itself is stronger than its adhesion for the glass

• IMF is stronger between mercury molecules than between mercury and the glass

vaporization

change from liquid phase to the gas phase

condensation

change from gas phase to liquid phase

vaporization and condensation are

opposite processes

in an open container

the net result is the rate of vaporization is greater then the rate of condensation, there is a net loss of liquid

in a closed container

the net result is that at some time the rates of vaporization and condensation will equal

dynamic equilibrium

when two opposite processes reach the same rate so that is no gain or loss if material

the weaker the IMF, the ____ the rate of evaporation

faster

rate of vaporization increases with ___ temperature

increasing

rate of vaporization increases with ___ surface area

increasing

• the more area exposed in an open container, the faster it will vaporize

volatile

liquids that evaporate easily

nonvolatile

liquids that do not evaporate easily

vapor pressure

the pressure exerted by the vapor when it is in dynamic equilibrium with its liquid

• the higher the vapor pressure, the weaker the IMFs

the higher the vapor pressure, the ___ volatile the liquid

more

normal boiling point of a liquid

its boiling point when surrounding pressure is equal to 1 atm= 760 torr=760 mmHg

heat of vaporization(or enthalpy of vaporization)

amount of heat energy required to vaporize one mole of the liquid

• it’s always endothermic, so it’s always positive

sublimation

solids transitioning directly into a gas state

deposition

gas substances condense directly into a solid state

heat curve of water

water freezes at 0 degrees Celsius, and boils at 100 degrees Celsius

phase diagram

on the lines, both states exist simultaneously

• for most substances, the freezing point increase as pressure increase

triple point

temperature and pressure at which all three phases of a substance coexists

critical point

specific temperature and pressure at which liquid and gas phases have the same density and are indistinguishable from each other

crystalline solids

its molecules, atoms, or ions are in patterns with long range and repeating order

amorphous solids

its molecules, atoms, or ions do not have any long-range order

• ex: glass

ionic solids

composed of positive and negative ions that are held together by electrostatic attractions

• high melting points

• hard, tend to be brittle

• do net conduct electrivity

metallic solids

atoms held together by metallic bonding

• high thermal and electrical conductivity, metallic luster, and malleability

• very hard and quite strong

• melting points of the metals vary widely

covalent network solid

solids held by a network of covalent bonds

• relatively strong

• hardness, strength, and high melting points

• not conductive

• ex: diamond, SiO2, SiC

molecular solids

solids composed of neutral molecules

• variable hardness

• variable brittleness

• not conductive

• low melting points

coordination number

number of other particles each particle is in contact with

packing efficiency

the percentage of volume in a unit cell occupied by particles

“like dissolves like”

a chemical will dissolve in a solvent that has a similar structure to the solvent

• polar molecules/ionic compounds will be more soluble in polar solvents

• nonpolar molecules will be more soluble in nonpolar solvents

miscible

liquids will dissolve in each other, they have the same polarities

hydrophilic

likes water

• OH, H2O, CHO, NH2

• polar

hydrophobic

afraid of water

• C-H, C-C

• nonpolar

for the solvent and solute to mix you must overcome

• all of the solvent-solute attractive forces or

• some of the solvent-solvent attractive forces

the solubility of a solute in a particles solvent is

the maximum concentration that may be achieved under given conditions when the dissolution process is at equilibrium

saturated

a solution that has the solute and the solvent in dynamic equilibrium

unsaturated

a solution that has less solute than saturation

super saturated

a solution that has more solute than saturation

colligative properties

properties whose value depends only on the number of solute properties, and NOT on what they are

the presence of nonvolatile solutes lowers the

vapor pressure of a solution

osmosis

the flow of solvent from a solution of low concentration into a solution of high concentration