Chemistry IMFS

Intramolecular Forces

forces within a molecule (covalent bonds)

Intermolecular Forces (Covalent Bonds)

Forces between molecules (IMFs)

IMFs are (stronger/weaker) than intramolecular forces

weaker, IMFs will break first

Phase Changes (Most likely caused by IMFS, what is the increasing IMFs trend?)

Gas--> Liquid--> Solid

IMFs are WEAKER than metallic or ionic bonds (only relevant in covalently bonded compounds)

okay

London Dispersion Forces (LDFs)

Everything has LDFs, most notable in nonpolar (no definitive positive and negative end) covalent compounds, greater electrons means stronger LDF

Polarizability (Explains LDF strength)

Ability to form instantaneous, temperary dipoles: Greater the number of electrons, greater the polarizability, and stronger the LDFs

Dipole-Dipole

Between polar (permenant uneven distribution of charge) molecules

Identify Dipole-Dipole

Different exterior atoms and asymetric (Bent, Trigonal Pyramidal, Seesaw or Sawhorse, T-Shaped, Square Pyramidal)

Ion-Dipole Forces

In which an ion is attracted to an oppositely charged polar molecule

Hydrogen Bonding

When Hydrogen is directly connected to NOF (internally)

How to determine which Hydrogen Bond is stronger

Greater Hydrogen Bonding regions (Number of lone pairs on NOF connected to H)

Boiling point

Stronger IMFs, Greater Boiling Point

If given data, follow the data NOT the trend

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Molecular (structure)

Molecules, IMFs

Molecular (Properties)

Lowest Melting point (<100 c), Never conducts electricity, Polar-soluble, Nonpolar-unsoluble, Ex: Ar, CO2, I2

Covalent Network (structure)

Atoms, Covalent Bonds

Covalent Network (Properties)

Highest melting point (1000+ c), Electrically conductive (Graphite-Yes, Everything else-No), Unsoluble, Ex: Sand (SiO2), diamonds, Quarts, glass, Graphites

Ionic (structure)

Cations & Anions, Lattice Energy

Ionic (Properties)

Medium melting point (100+ c), Liquid or Aqueous is conductive, Soluble (solubility rules) Ex: Na, Cl, CuSO4

Metallic (structure)

Metals, Sea of Electrons

Metallic (Properties)

Medium (100+ c), Always electrically conductive, Unsoluble, Ex: Cu, Au, Alloys

Allotropes

Different forms of an element in the same physical state (O2 and O3 or Diamonds and Graphites)

Properties are for Molecular liquid

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Viscosity (def.)

Resistance to flow, ease in which molecules flow with respect to each other

Viscosity (Relationship to IMFs and Temperature)

IMFs increase, Viscosity increase

Temperature increases (IMFs break), Viscosity decreases

Surface Tension (def.)

Uneven, unbalanced IMFs on the surface particles, measurement of inward forces that must be overcome to break the surface of liquid

Surface Tension (IMFs relationship)

As IMFs increase, surface tension increases

Capillary Action (definition)

tendency of liquids to climb narrow tubes, driven by adhesion and cohesion

Adhesion

Ability of particles to stick to other different things

Cohesion

Ability of particles to stick to themselves

Meniscus

the curve that exists on the surface of a liquid

Vapor Pressure

the pressure that develops in the gas phase when a liquid is placed in a closed container, high vapor pressure means liquids vaporize easily, not affected by volume

Vapor pressure (IMF, Temperature, and Molar Mass relationship)

As IMFs increase, Ability to turn into gas is lower, vapor pressure decreases

As temperature increases, vapor pressure increases

As molar mass increases, vapor pressure decreases

Triple point

Where all three phases exist at equillibrium

Solution

homogeneous mixture in which one substance is dissolved in another

Solute

substance being dissolved

Solvent

a substance doing the dissolving

Aqueous (aq) solution

a solution in which H20 is the solvent

Polar solvents dissolve polar molecules due to…

dipole forces

Nonpolar solvents dissolve nonpolar molecules due to…

LDFs (London dispersion forces)

Molarity (Concentration) equation

moles of solute/liters of solution (Add liters of solute and solvent)

Dilution (decrease in concentration) equation (mixing two solutions)

M1V1=M2V2

Beer's Law

direct relationship exists between amount of light absorbed and the concentration, A = εbc (Molar absorptivity e is constant), b (path length (how thick cuvette or beaker) cm), c (concentration M)

Distillation

process of seperating a substance due to differences in boiling point (lower boiling point is gas and higher boiling point stays liquid)

Distillate

Substance that turns into gas and later made back into a liquid

Filtration

Seperating solid and liquid (after percipitate is formed), filtered with porous membrane (S remains in paper while liquid passes through)

Chromatography

identifying contents of a solution due to differences in relative polarity, as the solvent moves up the stationary phase, substances more similar to a paper's polarity stick, while substances more similar to the solvents travel up with the solvent

(Relative Polarity) Rf

distance traveled by spot/ distance traveled by water

Greater the Rf values means

the more similar the spots polarity is to the solvents polarity

Ideal Gas Law

PV=nRT (same side inverse relationship, opposite side direct relationship)

Pressure

Force per unit area exerted by collisions of particles with each other and with their surroundings (atm)

Volume

Determined by the container

(extra gas does not change volume)

Diffusion

spreading out of a gas

Effusion

gas escaping through small pores in a container (Heavier the gas, the slower it moves--molar mass)

Daltons law of partial pressure

Collecting gas over water

Ptotal = P1 + P2 + P3…

P total = P (gas) + VP of H20

Maxell-Boltzmann Diagrams

Farther right (peak) increased energy and speed (bc of temp. or mass)

As temperature increases KE increases

okay

Heavier particle means slower velocity

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Kinetic molecular theory

model that predicts behavior of ideal gases as seen in the ideal gas law

Major assumptions for Ideal Gasses

1. Gas molecules move randomly and experience completely elastic collisions, no loss of energy (real gases have IMFs, cause them to stick)

2. Gas molecules have zero volume, however they have definite mass

3. Gas molecules in a sample are assumed to have a constant temperature

Real Gasses behave like ideal gasses under three conditions

1. Low IMFs

2. Raise Temperature, broken IMFs

3. Lower pressure, larger V and less interactions (2&3 make gasses behave ideally)