AP Chemistry Unit 3

Intermolecular Forces

attractions between entire molecules due to charge differences (positive or negative)

London Dispersion Forces

weakest typs of IMF and occur in all molecular samples (induced dipole)

Dipole-Dipole Forces

only occur in a sample of polar molecules and slightly stronger than LDFs

Hydrogen Bonding

strong dipole-dipole attraction between hydrogen directly bonded to F,O, or N in a molecule

Polarizability

ease with which the electron cloud of an atom or molecule is distorted

Ion-Dipole Attractions

only occur in a mixture of an ionic compound with polar molecules (strongest IMF)

Ion-Ion Attractions

occurs in a sample of ionic compounds; form a crystal lattice (salts)

Ionic Solids

held together by the mutual attraction between cations and anions

Covalent Network Solids

held together by an extended network of covalent bonds (diamonds/graphite)

Molecular Solids

held together by weak IMF

Metallic Solids

typically good conductors, malleable, and ductile (valence electrons are delocalized)

Crystal Lattice

a unit cell and the geometrical pattern of points on which the unit cells are arranged

Delocalized

when electric charge is spread over more than one atom (allows for conducting)

Substitutional Alloy

atoms of the minority element occupy positions normally occupied by atoms of the majority element (amongst)

Interstitial Alloy

atoms of the minority elements occupy interstitial positions that lie in the “holes” between atoms of the majority element (between)

Surface Tension

when molecules on a surface of a liquid experience a net inward force

Capillary Action

spontaneous rising of a liquid

Viscosity

measure of a liquid’s resistance to flow; stronger IMF, higher the viscosity (thickness)

Density

measures how compact a substance is (D = m / v)

Ideal Gas Law

PV = nRT

Combined Gas Law

P1V1 / T1 = P2V2 / T2

Dalton's Law of Partial Pressures

sum of all the partial pressures of each gas in a mixture of gasses is equal to the total pressure

Mole Fraction

denoted by Xa and equals moles A / total moles

The Kinetic Molecular Theory

Maxwell-Boltzmann Distributions

display the distribution of energy at given temperatures for a gas

Effusion

describes the passage of gas through a tiny space into a vacuum space

Diffusion

describes the mixing of gases (temperature ↑, rate of diffusion ↑) (bigger molecules slower diffusion)

Molarity

numbers of moles of a solute dissolved in 1 liter of solvent; M = m / L

Diluting Solutions

decreasing the concentration of a solute in a solution by removing solute or adding solvent

Mixtures

in which the macroscopic properties depend upon the location in the mixture

Wavelength

the length of one period of a wave

Frequency

describes the number of waves that pass a fixed place in a given amount of time and is measured in per-seconds

Solubility

amount of solute needed to form a saturated solution at any particular temperature