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Chemistry Final
concepts for final
45
Chemistry
Undergraduate 1
12/11/2011

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Term
Ionization Energy
Definition
the energy required to remove an electron from a gaseous atom or ion
trend: increases across period and up group (highest=He)
Term
Electron Affinity
Definition
the energy change associated with the addition of an electron to a gaseous atom trend: becomes more negative across period and up group (changes down group are small and numerous exceptions)
Term
Atomic Radius
Definition
half the distance between the nuclei in a molecule consisting of two identical atoms trend: decrease from left to right and increases down group
Term
Mixture vs. Pure Substance
Definition
mixture: variable composition (homogeneous (solution) or heterogeneous) pure substance: constant composition (element or compound)
Term
Law of Definite Proportion
Definition
A given compound always contains exactly the same proportion of elements by mass
Term
Law of Multiple Proportions
Definition
When two elements form a series of compounds the ratios of the masses of the second element that combine with 1 gram of the first element can always be reduced to small whole numbers
Term
Dalton's Atomic Theory
Definition
1. each element is made up of tiny particles called atoms
2. the atoms of a given element are identical, the atoms of different elements are different in some fundamental way or ways
3. chemical compounds are formed when atoms of different elements combine with each other. a given compound always has the same relative numbers and types of atoms
4. chemical reactions involve reorganization of the atoms, the atoms themselves are not changed
Term
Empirical Formula vs. Molecular Formula
Definition
empirical: simplest whole number ratio of the atoms in a compound
molecular: exact formula of molecule
Term
Strong Electrolytes vs. Weak Electrolytes vs. Nonelectrolytes
Definition
strong: completely ionize
weak: partially ionize
non: don't produce any ions
Term
Molarity
Definition
moles solute/Liters solution
Term
Solubility Rules
Definition
1. nitrate (NO3-) soluble
2. alkali metals and ammonium (NH4+) soluble
3. chloride, bromide, iodide soluble (except Ag+, Pb2+, Hg2 2+)
4. sulfate (SO4 2-) soluble (except Ba, Pb, Hg2, Ca)
5. hydroxides (OH-) slightly soluble (except NaOH, KOH)
6. sulfide (S2-), carbonate (CO3 2-), chromate (CrO4 2-), and phosphate (PO4 3-) slightly soluble
Term
Types of Chemical Equations
Definition
formula equation: reactants and products in undissociated form
complete ionic equation: all strong electrolytes shown as ions
net ionic equation: spectator ions eliminated
Term
Bronstead Acids and Bases
Definition
Acid: proton donator
Base: proton acceptor
Term
Arrenhius Acids and Bases
Definition
Acid: produces H+ ions (H3O+) in water
Bases: produces OH- ions in water
Term
Oxidation-Reduction Reactions (Redox)
Definition
electrons are transferred
oxidation: increase in oxidation state, loss of electrons
reduction: decrease, gain
oxidizing agent: electron acceptor
reducing agent: electron donator
Term
Gas Laws
Definition

Boyle: PV=k

Charles: V=bT

Avogadro: V=an

Ideal Gas Law: PV=nRT

molar mass=(dRT)/P

Dalton's Law of Partial Pressures: Ptotal=P1+P2+P3...

 

 

Term
Kinetic Molecular Theory Gases
Definition
1. volume is negligible
2. constant random motion
3. no repulsive or attractive forces
4. average kinetic energy in directly proportional to Kelvin temp
5. collisions with each other and container are elastic
followed at low pressure and high temperatures
Term
Endothermic vs. Exothermic
Definition
Exothermic: potential energy stored in bonds is converted to thermal energy, reactants have higher potential energy, bonds in products are stronger than reactants, more energy is released when new bonds in products are formed than is consumed to break bonds in reactants
Endothermic: energy flows into system as heat increases potential energy, products have higher potential energy and weaker bonds
Term
Thermodynamic Law-thingies
Definition
sum of kinetic and potential energies
ΔE=q + w
q: + energy added, - energy out
w: + surroundings do work on system, - system does work on surroundings
for gas work: w=-PΔV
Term
Enthalpy
Definition
H=E + PV
ΔH=qp (at constant pressure)
Hess's Law: enthalpy same regardless of steps
from bond energies: ΔH= Σn x D(bonds broken)-Σn x D(bonds formed)
Term
Calorimetry
Definition
constant pressure: energy released by reaction=specific heat capacity of solution x mass of solution x increase in temperature= s x m x ΔT
constant volume: ΔT x heat capacity of container
Term
Standard Enthalpy of Formation
Definition
change in enthalpy that accompanies the formation of one moles of a compound from its elements with all substances in their standard states Compound: gas at 1 atm, pure substance in condensed state is pure substance, solution is 1M Element: form at 1 atm and 25C ΔHf reaction=ΔHf products - ΔHf reactants
Term
Waves and craps
Definition
λv=c
Ephoton=hv=(hc)/λ
de Broglie's Equation: λ=h/(mv) to calculate wavelength of particle
Term
Quantum Numbers
Definition
n: principle quantum number
l: angular momentum, 0 to (n-1), shape 0=s, 1=p, 2=d, 3=f, 4=g
ml: magnetic, -l to l, orientation
ms: electron spin, -1/2 or 1/2
Term
Writing Electron Configurations Like a Boss
Definition
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p
number of orbitals per subshell: s=1, p=3, d=5, f=7, g=9
Term
Electronegativity
Definition
the ability of an atom in a molecule to attract shared electrons to itself
trend: fluorine highest, increases left to right, decreases down
Term
Isoelectronic Ions
Definition
same number of electrons
more protons=smaller
Term
Lattice Energy
Definition
the change in energy that takes place when separated gaseous ions are packed together to for an ionic solid, negative, exothermic
Term
Lewis Structures
Definition
1. Things can exceed the octet rule (I know, say whaaa?) like third row+ elements because of valence d orbitals
2. B and Be often have fewer than eight electrons, very reactive compounds
C, N, O, F always assumed to obey octet rule
Formal Charge: valence e- on free atom - valence e- assigned to atom in molecule, close to zero as possible and negative on most electronegative atom
Term
VSEPR (valence shell electron-pair repulsion) Model
Definition
2 effective pairs: linear, 180 3: trigonal planar, 120 4: tetrahedral, 109.5 (3: trigonal pyramidal, 2: bent) 5: trigonal bipyramidal, 120 & 90 (4: see-saw, 3: t-shaped, 2: linear) 6: octahedral, 90 (4: square planar)
Term
Hybridization
Definition
2: sp, 3: sp2, 4: sp3, 5: dsp3, 6: d2sp3
sigma bonds: between atoms, pi bonds: above and below atoms, double bond: one sigma + one pi
Term
Molecular Orbital Model
Definition
bonding: lower in energy, antibonding: higher in energy
bond order: (number of bonding e - number of antibonding e)/2, larger=stronger, larger bond energy, smaller length
paramagnetism=unpaired, dimagnetism=paired
B, C, N: sp mixing changes order O,F: no sp mixing
Term
Localized Electron Model
Definition
1. Lewis structure
2. Arrangement of electron pairs according to VSEPR
3. Specify hybridization
Term
Intermolecular Forces
Definition

dipole-dipole attraction: polar molecules

hydrogen bonding: strong dipole-dipole forces, when hydrogen is bound to highly electronegative atom (N, O, F)

london dispersion:induced dipole, polarizability: large atoms, more electrons higher

electrostatic attraction: ionic compounds

Term
Liquids
Definition
surface tension: resistance of a liquid to an increase in its surface area, high IM forces=high surface tension
capillary action: cohesive forces (IM between liquid molecules) and adhesive forces (between liquid and container, when container is polar)
viscosity: resistance to flow
Term
Solids
Definition
crystalline (regular arrangement, lattice) vs. amorphous (disorder)
types of crystalline: atomic, ionic, molecular
X-ray diffraction according to nλ=2dsinθ
Term
Unit Cells
Definition
Simple Cubic: 1 net sphere, side= 2r Body-Centered Cubic: 2, side= r4/sqrt(3) Face-Centered Cubic: 4, side=rsqrt(8), 8 tetrahedral holes, 4 octahedral holes
Term
Metals
Definition
closest packing: aba=hexagonal closest packed (hcp) structure, abc= cubic closest packed (ccp) structure, face-centered
Term
Vaporization
Definition
endothermic enthalpy of vaporization: energy required to vaporize 1 mol liquid at 1 atm higher IM forces, lower vapor pressure larger molar mass, lower vapor pressure (dispersion forces) higher temp, higher vapor pressure melting point: liquid and solid have identical vapor pressures
Term
Phase Diagrams
Definition
solid/liquid line sloped negative: solid less dense than liquid, melting point decreases as pressure increases
positive: solid more dense than liquid, melting point increases with pressure
Term
Henry's Law: gas solubility and pressure
Definition
C=kP
solubility increases when pressure increases
C=concentration of dissolved gas
P=partial pressure of gas solute above solution
k=constant for solution
Term
Molality
Definition
moles solute/kg solvent
Term
Temperature and Gas Solubility
Definition
gas solubility in liquid typically decreases when temp increases
Term
Vapor Pressure of Solutions
Definition
nonvolatile solute lowers vapor pressure of solvent
Raoult's Law: Psolution=Xsolvent x Pinitial of solvent (modified when both components are volatile)
Term
Colligative Properties: depend only on number of solute particles
Definition
Boiling Point Elevation: ΔT=Kb x molality of solute
kb=molal boiling-point elevation constat
Freezing Point Depression: ΔT=Kf x molality of solute
Osmotic Pressure: Π=MRT, M=molarity, T=kelvin temp, isotonic=identical, hyper=more concentrated solvent goes out, hypo=less concentrated, solvent comes in
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