Chemistry 111Final ExamChapter 5Bond AngleAngle (degrees) defined by lines joining the centers of two atoms to the center of a third atom to which they are covalently bondedVESPR TheoryA model predicting that the arrangement of valence electron pairs around a central atom minimizes repulsion to produce the lowest energy orientationElectron Pair Geometry3-dimensional arrangement of bonding e- pairs and lone pair electrons about a central atomMolecular Geometry3-dimensional arrangements of atoms in a moleculeTwo atoms bonded to central atom linear (180 degrees)Three atoms bonded to a central atom trigonal planar (120 degrees)4 atoms bonded to central atom tetrahedral (109.5 degrees)5 atoms bonded to central atom trigonal bipyramidal (90 to 120 degrees)6 atoms bonded to central atom octahedral (90 degrees)Bond DipoleSeparation of electrical charge created when atoms with different EN form a covalent bondPolar MoleculeSum of bond dipole vectors > zeroSigma BondCovalent bond having highest electron density between the two atoms along the bond axis. All bonds are sigma bonds. In a double or triple bond, one of the bonds is a sigma bond.Pi BondParallel p orbitals form pi bonds. A single bond is always a sigma bond, but a double bond has a sigma and a pi bondHybridizationMixing of atomic orbitals to generate new sets of equivalent orbitals that form covalent bonds with other atomsSp= 2 groups Sp2 = 3 groupsSp3= 4 groupsSp3d= 5 groupsSp3d2 = 6 groupsChapter 6Dispersion (London) ForcesIntermolecular force between nonpolar molecules caused by the presence of temporary dipolesin the molecules. (Nonpolar + Nonpolar molecules) every bond has dispersion forcesTemporary Dipole (Induced Dipole)Separation of charge produced in an atom or molecule by a momentary uneven distribution of electronsPolarizabilityRelative ease with which the electron cloud in a molecule, ion, or atom can be distorted, inducing a temporary dipoleSize of Atoms/MoleculesLarger atoms/molecules more polarizable than smaller atoms/smaller. Dispersion increases withpolarizabilityShape of MoleculesIncreased surface area = increased interactions between molecules. Linear molecules have higher dispersion than branched molecules of similar molecular weightDipole-DipoleAttractive force between polar moleculesHydrogen BondStrongest dipole-dipole interaction. Occurs between H atom bonded to a small, highly electro negative element (F, O, N) and an atom of oxygen O or N in another moleculeIon-DipoleAttractive force between an ion and a molecule that has a permanent dipoleSphere of HydrationCluster of water molecules surrounding anion in aqueous medium. Sphere of solvation if solventother than H2O. Like Dissolves Like:Ionic/polar solutes will be soluble in polar solvents.Nonpolar solutes will be soluble in nonpolar solvents.Percent CompositionThe composition of a compound expressed in terms of percentage by mass of each elementMass of element in compound x 100% mass of compoundEmpirical FormulaBased on the lowest whole number ratio of its component elementsExample:C4H8 reduces to CH2Na2O2 reduces to NaOEmpirical Formula vs Molecular FormulaEmpirical Formula:-Simplest whole-number ratio of elements in a compoundMolecular Formula:-Actual molar ratio of elements in a compound-Equal to whole number multiple of empirical formula-Need empirical formula and molecular formula If the molar mass is 26 g/mol, what is the molecular formula?Molar mass / empirical formula = 26 g / 134.44 = 2Percent YieldTheoretical Yield:The maximum amount of product possible in a chemical reaction for given reactant quantitiesActual Yield:Percent Yield = (Actual Yield / Theoretical Yield) x 100%Solutions: homogenous mixtures of two or more substancesSolvent: component of a solution that is presentSolute: any component in a solution other than the solventAmount of solute in a solution:Amount of Solute / Amount of SolventMolarity (M)M= (moles of solute/liter of solution) = n / v*As a conversion factor g of soluteMass of solute = (volume x molarity) x Mg = (L x mol / L) x g/molDilutionsStock SolutionA concentrated solution of a substance used to prepare solutions of lower concentrationStandard SolutionA solution whose concentration is fairly precisely knownDilutionProcess of lowering the concentration of a solution by adding more solvent(# moles solute) stock = (# moles solute) diluteElectrolytesStrong Electrolytes: (Na, K)-Nearly 100% dissociated into ions-Conduct current efficientlyWeak Electrolytes (weak acids)-Only partially dissolved into ions-Slightly conductiveCH3CO2H CH3CO2 (aq) + H (aq)NonelectrolytesSubstances in which no ionization occurs; no conduction of electrical currentAcid-Base Reactions:Acids: produce H3O in solutionBases: produce OH in solution*H3O simplified by leaving out water, often written just as HBronsted-Lowry definitions:Acids: proton (H) donorsBases: proton acceptorsHCl (donor/ acid) + H2O (acceptor / base) H3O + ClStrong Acids / Bases:Dissociate completely in aqueous solutionStrong Acids: HCl, HBr, HI, H2SO4, HNO3, HClO4Examples:H2SO4 H + HSO4HNO2 H + NO2Strong BasesNaOH Na + OHWeak BasesNH3 + H2O NH4 + OHWater as a Base:HCl (donor) + H2O (acceptor) H3O + ClNeutralizationReaction that takes place when an acid reacts with a base producing a solution of salt in waterSaltPb (NO3)2 (aq) + 2NaI (aq) PbI2 (s) + 2 NaNO3 (aq)Saturated SolutionA solution that contains the maximum concentration of solute possible at a given temperatureSupersaturated SolutionContains more than the maximum quantity of solute predicted to be soluble in a given volume of solution at a given temperatureOxidation – Reduction ReactionsOxidationReaction that increases oxygen content of a substance (loss of electrons)4Fe (s) + 3O2 (g) 2Fe2O3ReductionReaction involving loss of O2 (gain electrons)Fe2O3 (s) + 3CO (g) 2Fe (s) + 3CO2REDOX: transfer of
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