GenChem2 Unit1

Dipole-dipole attractions

attractive forces between oppositely charged ends of polar molecules

Hydrogen bonding

strong type of intermolecular dipole-dipole attraction. Occurs between hydrogen and F, O or N

London dispersion force

the intermolecular attraction resulting from the uneven distribution of electrons and the creation of temporary dipoles

Rank the strength of different types of bonding

1. Covalent
2. Hydrogen
3. Dipole-dipole
4. London dispersion

Higher melting and boiling point corresponds with

Larger mass

Cohesive forces

intermolecular forces that bind similar molecules to one another

Viscosity

A liquid's resistance to flowing

Viscosity increases as _____ increase

IMF's

Viscosity decreases as _____ increases

temperature

Surface tension

A measure of how difficult it is to stretch or break the surface of a liquid

Adhesive forces

intermolecular forces that bind a substance to a surface

Capillary action

the combined force of attraction among water molecules and with the molecules of surrounding materials

Crystalline solids

well-ordered structure that is regular and repeating; small impurities change its properties

Amorphous solids

solids that lack order; often occurs when solid changes quickly

Ionic solid definition

solid composed of positive and negative ions held together by strong electrostatic attractions

Ionic solid characteristic

hard, brittle, somewhat high melting points

Metallic solids definition

Collection of metal atoms in a sea of shared electron

Metallic solids characteristics

Conducts electricity and heat well, malleable, high melting points

Covalent network

strongly bonded, very hard, high melting points, not conductive

Molecular solids

neutral molecules held together with IMF's, low melting points

Melting/fusion

solid to liquid

vaporization

Liquid to gas

freezing

liquid to solid

condensation

Gas to liquid

sublimation

solid to gas

depositon

gas to solid

Enthalpy

the heat content of a system; ΔH

ΔH followed by a phase change is

the energy required for that phase change

Lower vapor pressure is due to ______ IMF's

higher

Vapor pressure

the pressure caused by the collisions of particles in a vapor with the walls of a container

Vapor pressure equation

ln(P2/P1) = (ΔHvap / R)(1/T1 - 1/T2)

Boiling point

Temperature where equilibrium vapor pressure is equal to ambient pressure

Dispersion forces are felt by...

all molecules

Dipole-dipole attractions are felt by...

only polar molecules

More electrons --> _____ dispersion forces

higher

Energy equation between phase changes

q=mcΔT (J)

IMF for molecular solids

dipole

IMF for ionic solids

ionic-bonds

IMF for atomic group 8A solids

LDF

IMF for atomic network solids

Covalent bonds

IMF for metal solids

metal bonds

metallic bonding

the chemical bonding that results from the attraction between metal atoms and the surrounding sea of electrons

covalent bonding

a bond formed when atoms share one or more pairs of electrons

Higher vapor pressure ---> ______ volatility

lower

Energy equation during phase changes

q=nΔH (kJ)

Organic compounds always contain...

carbon

Organic compounds are almost always ______ compounds

molecular

Ionic compounds are almost always ______

inorganic

Alkanes

-saturated hydrocarbons
-single bonds only
-four bonds per carbon

Isomers

same formula, different structures

Ideal solutions

IMF in the solutions is not different from the solute-only or solvent-only materials

Henry's law equation

C=kP

Ionic compounds dissolve in ______ solvents

polar

Molecular polar molecules dissolve in ______ solvents

polar

Molecular nonpolar molecules dissolve in ______ solvents

nonpolar

compounds with a special IMF (like H-bonding) dissolve best in compounds with the _______(same/different) IMF

same

Miscible

mixes in all proportions (same polarity)

Immiscible

Forms a layer (different polarities)

Electrolyte

Solvent pulls the solid apart to form ions, conducts electricity

Raoult's law

Psolution = Xsolvent x Psolvent

Vapor pressure of solvent is _______ as more stuff is added

lowered

Mole fraction equation

moles of solute/total moles

Molality equation

moles of solute/kg of solvent

Van't Hoff Factor

- total # of of particles in solution
- Ex: glucose is 1
- Ex: NaCl is 2 (breaks up into 2 ions)

Boiling point elevation

ΔTb = i(Kb)m

Freezing point depression

ΔTf = i(Kf)m

Suspension

large particles, settle out after a while

Colloids

substances such as large protein molecules that do not readily dissolve into true solutions but do not settle out