12 Intermolecular Forces - Loyola University Chicago
FITCH RulesGeneral“A” students work(without solutions manual) 10 problems/night.Office Hours W – F 2-3 pmModule #12Intermolecular ForcesProperties and tmcm3gramReference Statesize of earthmmass of 1 cm3 water at specified Temp(and Pressure)oC, Kboiling, freezing of water (specifiedPressure)amu(mass of 1C-12 atom)/12atomic mass of an element in gramsatm, mm Hgearth’s atmosphere at sea level1.66053873x10-24gquantitymolePressureEnergy, GeneralAnimal hphorse on tread millheatBTU1 lb water 1 oFcalorie1 g water 1 oCKinetic Jm, kg, sElectrostatic1 electrical charge against 1 Velectronic states in atom Energy of electron in vacuumElectronegativity FHeat flow measurementsconstant pressure, define system vs surroundingsper mole basis (intensive)ChemistryAlanah FitchFlanner Hall 402508-3119afitch@luc.eduG1: Suzuki is SuccessG2. Slow me downG3. Scientific Knowledge is ReferentialG4. Watch out for Red HerringsG5. Chemists are LazyC1. It’s all about chargeC2. Everybody wants to “be like Mike” qq C3. Size Matters E k r r C4. Still Waters Run DeepC5. Alpha Dogs eat first1 2el12Intermolecular Forces1. Evidence for Intermolecular Forces2. Phase Diagrams (briefly)3. Liquid-Vapor Equilibrium1. Kinetic theory2. Gas escape as a way to measure liquid intermolecular forces4. Boiling points related liquid Intermolecular Forces1. Dipole-dipole2. Dispersion3. H-bonding4. example application – heat capacity of lakes5. Solid Intermolecular Forces1. Molecular Solids (Dispersion/ H-bonding)2. Network Covalent (Covalent) – example glass3. Ionic solids (Ion/ion)4. Metallic solids (metal bonding)6. Structures of Crystals1. Unit Cells2. Common Metal Unit cells1. Calculate density of lead3. Common Ionic Solid Unit cells1. Calculate density of ionic solid1
We learned about“Ideal” behavior of gases - do not notice each otherViolate Rules #C1 (charge) & C3 (size)But - we have accumulated evidence that moleculesa) Real gases “notice” each otherb) Condensed phase (liquids, solids) notice each otherV1 Vmolarvolume [ RT ]nPReal gases volume are “smaller” than expected suggesting that they see each otherand move to each otherWhat evidence have we accumulated?deviationRobert Boyle, 1660; Boyle’s LawIntermolecular ForcesSpecific heatsMaterial Specific Heats c, cific heat ofWater increases toA dramatically largeValue from gasTo liquid (moreCondensed – see eachOther more) phase1. Evidence for Intermolecular Forces2. Phase Diagrams (briefly)3. Liquid-Vapor Equilibrium1. Kinetic theory2. Gas escape as a way to measure liquid intermolecular forces4. Boiling points related liquid Intermolecular Forces1. Dipole-dipole2. Dispersion3. H-bonding4. example application – heat capacity of lakes5. Solid Intermolecular Forces1. Molecular Solids (Dispersion/ H-bonding)2. Network Covalent (Covalent) – example glass3. Ionic solids (Ion/ion)4. Metallic solids (metal bonding)6. Structures of Crystals1. Unit Cells2. Common Metal Unit cells1. Calculate density of lead3. Common Ionic Solid Unit cells1. Calculate density of ionic solid2
PHASE CHANGES – related to Intermolecular ForcesSome tionheatheatcoolcoolHeat aleneHeat 21835729.630.840.743.359.4mp(oC) Hbp(oC) H vaporizationfusionSubstanceBoiling pointkJ / molkJ / molmp(oC) H fusion bp(oC) H What doyou see?What doyou see?What doyou see? H vaporization H fusionThe heats of fusion and vaporization are a way of describing the energy required to breakintermolecular forces sufficient to melt or vaporize the material; trends differ because solid,liquid structures of same substance can be very differentMelting pointPHASE CHANGES – related to Intermolecular ForcesOne formOf A PhaseDiagramPHASE CHANGES – related to Intermolecular ForcesEnergy required to move moleculesFurther apart (solid to liquid)3
Coulomb’s lawG1: Suzuki is SuccessG2. Slow me downG3. Scientific Knowledge is ReferentialG4. Watch out for Red HerringsG5. Chemists are LazyC1. It’s all about chargeC2. Everybody wants to “be like Mike” qq C3. Size Matters E k r r C4. Still Waters Run DeepC5. Alpha Dogs eat firstk (Q1 )(Q2 )E electrical energy of interactionK constant, 8.99x10-9J-m/C2Q charge on ion, 1.602x10-19Cr ionic radiusReference state is some very far distanceWhere they don’t see each other, 0 E of interactiond, Angstroms02finalinitial246810120 -200kJ interaction per mole-400kJ/mol-1400kJ/mol 1000kJ/molel1E dd rcation ranion1 2--400-600-800-1000-1200-1400 --1600Costs energy to move apartPHASE CHANGES – related to Intermolecular ForcesPHASE CHANGES – related to Intermolecular ForcesRepresents increaseIn kinetic energy ofMolecules movingE k 21 mv 2And increasing distance(electrostatic energy)d, Angstroms00-200kJ interaction per moleChemistryGeneralFITCH Rules-400-60024681012Represents kinetic energy neededTo escape solution-800-1000-1200-1400-16004
Example Problem: What energy is required to take 100.0 gOf water at 57 oC into the gas phase? The heat of vaporization ofwater at 100oC is 40.67 kJ/mol, cwater is 4.184 J/g-K 40 mol 40.67.67kJkJ 100 225.94 kJ100gHgH22OO 100100o oCC 18 g molHHOOatat100o o mol 100 CC 22[[]]q cm T 4.184 J q (100.0 g )[(100 273) K ( 57 273) K ] g K q 17,991JTotal q H vap225.94 kJ 17.9 kJ 2438444. 244.8kJWhat was the most “costly” part of the process?PHASE CHANGES – related to Intermolecular ForcesIntermolecular Forces1. Evidence for Intermolecular Forces2. Phase Diagrams (briefly)3. Liquid-Vapor Equilibrium1. Kinetic theory2. Gas escape as a way to measure liquid intermolecular forces4. Boiling points related liquid Intermolecular Forces1. Dipole-dipole2. Dispersion3. H-bonding4. example application – heat capacity of lakes5. Solid Intermolecular Forces1. Molecular Solids (Dispersion/ H-bonding)2. Network Covalent (Covalent) – example glass3. Ionic solids (Ion/ion)4. Metallic solids (metal bonding)6. Structures of Crystals1. Unit Cells2. Common Metal Unit cells1. Calculate density of lead3. Common Ionic Solid Unit cells1. Calculate density of ionic solidFor a bubble to breakPbubble PvaporAtB. P.How doesPressure affectWhat isGoing on?5
HHow do we get the heat ofvaporizationAndWhat is it related to (what“picture” should we have)?OHHOHHOHHHHOHOOHHOHOOHHOHHHHHHHOOnly 1 of 2 times water “hits” theSurface does it actually haveEnough energy to leave.OOµ3kTRT 1E k mass of 2 3kT molecule mass of molecule molecule 3kT Ek 2 OHHσg moleculeOHHO1 2mv21E k mass of221HHEk urms HHHFrom earlier chapter we learned of kinetic energy:Maxwell’s Distribution 3kT mass of molecule f ( x) e1 x µ 2 2 σ αEK2However, only a fraction ofmolecules at a given emperature thataverage speed, and therefore,Average energyIf you assume a normal distributionfor the “bell curve” you can calculatethe fraction of molecules with anenergy above the average valuef ( x) e E moleculekT e E moleRTHHFraction of collisions in which theenergy is sufficient to allow water toleave the liquid stateOHHfraction fOHHOHHHHHOHOHHOOHHHH1 Ea T R ln f 1 Ea T R ln P 1 Hvaporization T R HHOEaRTHOHOOnly 1 of 2 times water “hits” theSurface does it actually haveEnough energy to leave.OHHH2OHOHOHHOln f H1HHOOHHf e Kinetic theory involves an energy to break out of waterH6
ChemistryGeneralFITCH Rulesln P G1: Suzuki is SuccessG2. Slow me downG3. Scientific Knowledge is ReferentialG4. Watch out for Red HerringsG5. Chemists are LazyC1. It’s all about chargeC2. Everybody wants to “be like Mike” qq C3. Size Matters E k r r C4. Still Waters Run DeepC5. Alpha Dogs eat first1 2 J 1 Hvaporization 1 mol JT RK mol K Which value of “R” doWe use?ln P 1 H vaporization T R 2L atmmol KJR 8.31mol Kg m2R 8.31x10 3 2s mol KR 0.0821Check data – should be able to getHeat of vaporization for water 40.7kJ/molln P 1 Hvaporization T R yxel1Rule G5: Chemists areLazy:A slope1 H vaporization bT1 R 1 Hvaporization ln P2 bT2 R H vaporization slope .K 51651R ln P1 J JkJ H vaporization 51651. K 8.3145 42945.2 42.9mol K molmol ln P1 “Real” value40.71T1 H vaporization 1 ln P2 RT2 H vaporization R 1 H vaporization 1 H vaporization ln P2 ln P1T2 RR T1 The intercept “b” is annoying.Get rid of it.ln P 1 Hvaporization b T R ln P2 ln P1 1T2 H vaporization 1 R T1 H vaporization R P Hvaporization 11 ln 2 R P1 T2 T1 7
P Hvaporization 11 ln 2 R P1 T2 T1 Galen, 170Marie the Jewess, 300Charles AugustinJames WattCoulomb 1735-1806 1736-1819Jabir ibnHawan, 721-815Luigi Galvani1737-1798Galileo Galili1564-1642An alchemistCount AlessandroGuiseppeAntonio AnastasioVolta, 1747-1827Amedeo n Dalton1766-1844Abbe Jean Picard1620-1682William Henry1775-1836physicianDaniel Fahrenheit1686-1737Blaise Pascal1623-1662Jacques Charles1778-1850Robert Boyle,1627-1691Georg Simon Ohm1789-1854Michael Faraday1791-1867Isaac Newton1643-1727B. P. EmileClapeyron1799-1864Anders Celsius1701-1744Germain Henri Hess1802-1850Clausius-Clapeyron equation 1834Thomas GrahamJustus von Liebig1805-1869(1803-1873Rudolph ClausiusPolish born German1822-1888Mathematical Physics P Hvaporization 11 ln 2 PRTT1 1 2Benoit Paul EmileClapeyron1799-1864, FrenchEngineerMathematical physicist(developed concept ofentropy)Example, Calculate the heat ofvaporization for lead knowing that thevapor pressureOf elemental lead is 1 mm Hg at 987 oCand 10 mm Hg at 1167o C. 11 1mm Hvaporization ln 10mm 8.31 J (273 987) K (273 1167) K mol K H 11vaporization 2.302 J (1260) K (1440) K 8.31 mol K H vaporization 11 7.9365x10 4 6.9444 x10 4 2.302 KK J 8.31 mol K H1vaporization 9.9205x10 5 2.302 JK 8.31 mol K [ 2.302]8.31 molJ K 9.92063x10 51K Hvaporization J 1928755798. mol Hvaporization kJ Hvaporization 192.9molJ. Willard Gibbs1839-1903Richard AugustCarl EmilErlenmeyer1825-1909Ludwig Boltzman1844-1906Henri LouisLeChatlier1850-1936James Joule(1818-1889)Rudolph Clausius1822-1888Johannes Rydberg1854-1919J. J. Thomson1856-1940William ThompsonLord Kelvin,1824-1907Heinrich R. Hertz,1857-18941825-1898Johann BalmerMax Planck1858-1947Francois-MarieRaoult1830-1901Svante Arrehenius1859-1927James Maxwell1831-1879Walther Nernst1864-1941Dmitri Mendeleev1834-1907Fritz Haber1868-1934Johannes D.Van der Waals1837-1923Thomas MartinLowry1874-1936Fitch Rule G3: Science is ReferentialGilbert Newton Lewis1875-1946Johannes NicolausBronsted1879-1947Lawrence J. Henderson1878-1942Niels Bohr1885-1962Erwin Schodinger1887-1961Louis de Broglie(1892-1987)Friedrich H. Hund1896-1997Fritz London1900-1954Wolfgang Pauli1900-1958Werner KarlHeisenberg1901-1976Linus Pauling1901-1994Intermolecular Forces1. Evidence for Intermolecular Forces2. Phase Diagrams (briefly)3. Liquid-Vapor Equilibrium1. Kinetic theory2. Gas escape as a way to measure liquid intermolecular forces4. Boiling points related liquid Intermolecular Forces1. Dipole-dipole2. Dispersion3. H-bonding4. example application – heat capacity of lakes5. Solid Intermolecular Forces1. Molecular Solids (Dispersion/ H-bonding)2. Network Covalent (Covalent) – example glass3. Ionic solids (Ion/ion)4. Metallic solids (metal bonding)6. Structures of Crystals1. Unit Cells2. Common Metal Unit cells1. Calculate density of lead3. Common Ionic Solid Unit cells1. Calculate density of ionic solid8
Molecular Substances, Liquids: Intermolecular Forces1. Uncharged non conductors of electricity when pure (I2)2. Uncharged nonsoluble in watersoluble in nonpolar solvents such as CCl43. Uncharged low interactions holding them in liquid low boiling points4. Uncharged low interactions holding them in solid low melting points I I Holding mass approximately 60bp 78162bp (oC)-192-88-6297Look at one polarmoleculeNon polar moleculesBoil at lower temperature Both have same electroNegativity so equallyShare electrons in the bonds non polarTotal valence electrons:skeleton bondremaining electronsrequired for octets 14-21212I Cl Who pulls electronsBest?PermanentDipole momentsaffectboiling pointHolding mass approximately constant:formulaN2SiH4GeH4Br2g/mol283277160bp bp (oC)-192-88-6297Non polar moleculesBoil at lower temperatureBoiling point canIncrease if theMolar mass goes upWhy?9
Dispersion (London) ForcesTwo bath tubs with sloshingWater separated by rubberee e e e ee ee eeeTemporaryNegativechargeE Largest possible wave crests at each end of bathtubee e e e ee ee eeetemporaryPositivechargek (Q1 )(Q2 )Oscillations of electronsSet up temporary andOppositely chargedDipoles which attractEach otherLondon dispersionAlso referred to asVan der Waals forcesdd rcation ranionPlace two bathtubs end to end with a rubber divider:As one wave piles up the water in theBathtub responds creating a sympatheticWaveDispersion forces arise from induced or temporary dipolesEffect depends upon1.number of electrons in the molecule2.ease of creating a bathtub wave(less rigidity or spatial fixedness of electron)3.distance from nucleus (depth in periodic chart)Schroedinger Fritz London1928Fritz London1900-1954Born Breslau, GermanyDuke University physical chemistHeNeArKrg/mol4204084bp (C)-269-246-186-152What explainsThis trend?10
As the molar mass goes upboiling point goes up due to dispersion forcesDifferent slopes say something about induced dipole momentsElectronegativityH2OSomething unusual happens hereWhat do these guys have in common?Think of the Lewis dot structuresThink of Whom H is bonded toHFGroup16H2TeSbH3H2SeNH3AsH3Group15PH3 H F H F HIH2SGroup17HBrHydrogen is bonded with three highly electronegative speciesAlso having unpaired electrons N, O, FHClHydrogen loses control of most of its shared electron and is anUnhappy camper – needs more electronsElectronegativityFFNHHOHOHHNHOWhy not HCl also, similar in electronegativity to oxygen and nitrogen?.Hydrogen bonds are formed in each caseE k (Q1 )(Q2 )dd rcation ranionDo you see anything here?Need to be able to get close to the othermolecule, - small size matters11
Example: Would you expect to find hydrogen bonds in hydrazine? (Rocket fuel),N2H4Valence shell electrons: 2(N)4(H)2(5)4(1)TotalSkeleton structure H2N-NH2Single bonds5(2)Remaining electronsBoth have lone pair (unbonded) electrons on one of the three elements weAre interested in (N, O, F).10414-104Example: Would you expect to find hydrogen bonds in Dimethyl etherVs ethyl alcohol?HH N N HH H H N N HH HH H C C O H H HH C O C H HHBut hydrogen is not bonded tothe atom in dimethyl ether –expect no hydrogen bondingIn Ethyl alcohol hydrogen isbonded to oxygen. Expecthydrogen bondingH HHydrogen Bonding explains much of what we haveLearned about water.MaterialSpecific Heats c, Hydrogen bonding gives a low density structure in icedliquidH2 O 1000.d solidH2 O 0.917gcm30o Cgcm30o C H O H Hydrogen bonded ice structure12
Nutrient Cycling in Lake Michigan“A” students work(without solutions manual) 10 problems/night.Alanah FitchFlanner Hall 402508-3119afitch@luc.eduOffice Hours W – F 2-3 pmParticulate matter asMeasured by satelliteReflection measurementsA late spring phenomenaModule #12Intermolecular ForcesSurface temperature rises, Ice melts,becomes more dense,falls to bottompushing up nutrientRich particulate matter which feedsThe spring algaeIntermolecular ForcesSummary of Intermolecular Forces in LiquidsDipole/dipoleDispersion (bathtubs)Hydrogen bondingEffect Observed as:boiling pointsmelting pointsheat capacityvapor pressure of liquidHeat of fusionHeat of vaporizationWater and it’s density!Effects also observed for molecular solids1. Evidence for Intermolecular Forces2. Phase Diagrams (briefly)3. Liquid-Vapor Equilibrium1. Kinetic theory2. Gas escape as a way to measure liquid intermolecular forces4. Boiling points related liquid Intermolecular Forces1. Dipole-dipole2. Dispersion3. H-bonding4. example application – heat capacity of lakes5. Solid Intermolecular Forces1. Molecular Solids (Dispersion/ H-bonding)2. Network Covalent (Covalent) – example glass3. Ionic solids (Ion/ion)4. Metallic solids (metal bonding)6. Structures of Crystals1. Unit Cells2. Common Metal Unit cells1. Calculate density of lead3. Common Ionic Solid Unit cells1. Calculate density of ionic solid13
H bonds (kJ/mol)17-40Van der WaalsCovalent Bond Energies for bonds inside a moleculethat we haveBondBondEnthalpyalreadyLengthSingle BondexaminedpmkJ/molNetwork Covalent, Ionic, and Metallic SolidsC--CC--NC--OC--SC--FC--ClC--BrC--IForces between moleculesdispersiondipole/dipoleH-bondingTendency towardssoftness, low 330288216Graphite(pencil lead)Is a molecular solidCovalent bonds in solidsThese are allCovalent bonds!(to O)Glass formershave intermediatebond energies withOxygenSiSi-O-Si- .Crystal structure of quartzCovalent bonds in the network imply1.high melting points ( 1000oC)2.insoluble in all common solvents (solventscan’t break the bonds)3.poor electrical conductors (like molecularsolids)Glass making from 2000 B.C. Egypthow did they do it?What do youobserve?Could not get temperatures 1000oC. kJ 4.184 kJ 106kcal 443504 1kcal mol molMaximum value of glass formers is: 498 kJ/mol for Boron14
Glass formershave intermediatebond energies withOxygen, also havethe ability to createthree or morebondsGlassformersRule: Size Matters!Also have a particular smallRadius with respect to oxygen.Need to form tetrahedraHow did the Egyptians do it? – a topic to exploreB. E .SiO 2 443504. kJmol H f ( SiO ) 2Network Covalent, Ionic, and Metallic SolidsWhy is mp so high when enthalpy of fusion is not?Hint: naphthalne a large (multimolar) solid?14.22 kJmolmp(oC) Hbp(oC) H 40.730.843.3Typical fire temp 500-600oCTypical chimney fire temp 1000oCWhat Rule(s) Do WeInvoke Here?Charged ions1. strong electrostatic interaction high melting point (600-2000oC)15
Network Covalent, Ionic, and Metallic SolidsE k (Q1 )(Q2 )Coulomb’s lawdd rcation ranionE electrical energy of interactionK constantQ charge on ionr ionic radiusExplain this difference in melting points?NaClKBrWhat Rule(s) Do WeInvoke Here?mp oC801734No Clean SocksCuSO4 ( s ) Cu(2aq ) SO42( aq ) H O 6615. kJH 2 SO4 ( l ) H ( aq ) HSO4 ( aq ) H O 73.3kJWhat do you observe?How do you explain it?Oh Card me PleaSeCuS ( s) Cu(2aq ) S (2aq ) H O 14.5kJCharged ions1. strong electrostatic interaction high melting point (600-2000oC)2. Strong electrostatic interaction fixed positions no electrical conduction3. Most (not all) soluble in water (polar waterorganizes around the ions and satisfies theircharges)Network Covalent, Ionic, and Metallic SolidsH bonds (kJ/mol)17-40Van der WaalsCovalent (kJ/mol)64-1500 in molecules600 in solidsIonic (kJ/mol)600-1000Metallic bonds (kJ/mol)100-800e-H 3 PO4 ( l ) H ( aq ) H 2 PO3 ( aq ) H O 201. kJMetal solids1. No covalent bonding2. But strong attraction holds atoms in fixed lattice points3. Attraction is greater than H bonds or van der Waals forces4. Metallic bonds can be as strong as ionic bonds5. Sea of fluid electrons flows around the fixed metal ionsDetermines properties16
Melting point: Lowest meltingpoint occurs when electrons areleast “fixed” around metal cations– related to filling of thevalence shell electrons, andsolid structure structureThe seven metals earliestDiscovered have lowMelting pointsA lead “came” factoryCame is used to bendAround pieces of cutGlass for stained glasswindowsFluid electron sea explains1.high electrical conductivity2.high thermal conductivity: heat is carried by electron collisions3.Ductile, malleable, electrons are a flexible glue4.Luster, electrons not restricted to specific bonds5.Insoluble – electrons are not solubleFluid electron sea explains1.high electrical conductivity2.high thermal conductivity: heat is carried by electron collisions3.Ductile, malleable, electrons are a flexible glue4.Luster, electrons not restricted to specific bonds5.Insoluble – electrons are not soluble6.Can have relatively low melting pointsIntermolecular ForcesLow Melting PointHigh Melting point( 1000 oC)High Melting Point(600-2000 oC)Variable Melting PointNonconducting ofelectricityNonconducting ofelectricityNonconducting ofelectricityConductor ofElectricityInsoluble in WaterInsoluble in allcommon solventsMost are soluble inwaterInsolubleLow Boiling PointHigh Thermal ConductivityDuctile/MalleableLuster1. Evidence for Intermolecular Forces2. Phase Diagrams (briefly)3. Liquid-Vapor Equilibrium1. Kinetic theory2. Gas escape as a way to measure liquid intermolecular forces4. Boiling points related liquid Intermolecular Forces1. Dipole-dipole2. Dispersion3. H-bonding4. example application – heat capacity of lakes5. Solid Intermolecular Forces1. Molecular Solids (Dispersion/ H-bonding)2. Network Covalent (Covalent) – example glass3. Ionic solids (Ion/ion)4. Metallic solids (metal bonding)6. Structures of Crystals1. Unit Cells2. Common Metal Unit cells1. Calculate density of lead3. Common Ionic Solid Unit cells1. Calculate density of ionic solid17
CRYSTAL STRUCTURESMacroscopic MineralsMacroscopic Structures of MineralsMacroscopic Crystal FormIsometricHexagonalTetragonalWulfenite, tetragonal PbMoO4Not squarePbS, cubic,galenaOrthorhombic MonoclinicTriclinicCrocoitemonoclinicPrCrO4METAL CRYSTAL STRUCTURESMacroscopic Structures are often driven byThree dimensional microscopic organization of atoms or ionsMacroscopic Structures are often driven byThree dimensional microscopic organization of atoms or ionsThere are 14 kinds of basic microscopic organizational structures (unit cells).Simplest unit cellIs cubicAtoms/unit cell124CommonMetalstructuresFollow the corner atomEach of 8 corner atomsis shared by eight cells 1 atom/cell7 groups of unit cellsEach of 6 face atoms are shared by two cellsTotal atoms 6face/2 8corner/8 4 Total atoms 1body 8corner/8 218
Simple cubic1bccAtoms/unit cellGeometry24r s 32r sd 2 d12 s 2d2 d2 d2 d12 s 2(2s 2)2s4rAtoms/unit cellGeometry2r sbcc24r s 3rd1 2r3s 2Simple cubicAtoms/unit cell 1Geometry2r s%empty space 47.62s 2d1 s 2sd2 44r s 2d12 s 2 s 2s s2fccd 1 4rrd1 2 s 22s 2 s 2Simple cubic1fcc4d2 s 34r s 24r s 3bccfcc24r s 332.044r s 226.0Example: Calculate the density of lead from its molar mass and the fact that itHas a face centered cubic structure and bond length for elemental lead (centerof one atom to another) 349.9 pm for elemental lead.Complicated example from some textbook.What do we know?What do we need to know?Empty spacerelated toorganization ofatomsNumber of metalshaving thisunit cell shapeUnstable20 metals40 metalsPb19
Example: Calculate the density of lead from its molar mass and the fact that itHas a face centered cubic structure and bond length for elemental lead (centerof one atom to another) 349.9 pm for elemental lead.d ensity gcm 31. Need volume4r s 2a) fcc determinesb) side, s, of cubec) s3 is volumeBond length 2r2. Need radiusa) fcc determines bond lengthb) bond length represents sum of 2 radii3. Need massa) fcc determines4 atoms/volumeb) number of atomsc) convert atoms to moles to gramsWant in cm3Example: Calculate the density of lead from its molar mass and the fact that itHas a face centered cubic structure and the bond distance of 349.9 pm forelemental lead.2r 349.9 pm 349.9 pm 1m 100cm 10r 1012 pm m 174.95x10 cm2 4r s 2fcc4atomsmolg 207.2 g . 1137. x10 22 cm3 6.02 x1023 atoms mol cm3 1214(174.95x10 10 cm) s2This calculated value isconsistent with thereported value of 11.34g/cm3s 494.8 x10 10 cms 3 V [ 494.8 x10 10 cm] 121. x10 22 cm 33Atoms in a face centered cubic cell: 8corners/8 6faces/2 4We now know atoms/cm3; what next?20
4,000 deathsof mute swansin England/yearfrom fishingsinkersO’Halloran , 1988Rate of CoolingRelated to Heat capacity;For lead is low;To create spherical Lead shot,Want the material To solidifyBefore it hits to Ground so itDoes not deformMaterial Specific Heats c, p cool H f , Pb 512.kJmolm. p. Pb 327.3o Cgd Pb 1134.3cmBullet technology“muck” grazing birds, pickUp solid lead as a “pebble” toGrind in their gizards Energy cost to melt (low)Rate of cooling (heat capacity) fastSurface tension and deformation**Density (for final use as a bullet)Uses of lead: summary to date:Lead - useful material for environmental transport studies (isotopes)Lead - Lead acetate – used to “sweeten” wines; easily made from lead and wineLead – lead azide (firing ranges)(Electron transfer reactions; low melting points)Lead – soldering (radiators, cars, electronics)(Low vapor pressure)Lead – malleable metal (roofs, downspots, stained glass)(Metallic bonding, heat capacity)Lead - Glasses and glazes (pottery) Low energy requirements(Group 4 covalent network with extra electron pair “spaghetti”Lead - Solvent for other metals: purifying silver (Greek/Roman production)(Group 4 covalent network with extra electron pair “spaghetti”Lead - Density of solid good Xray shieldLead – low melting point, high density bullets (low energy requirements)Toxicity of lead: summary to date:Covalent and Ionic bondingSimilar ionic size to Ca2 Same charge as Ca2 Electrostatic attraction of lead to calcium binding sites will be similarDifference: has s2 electrons – distorts binding in biomolecule21
Ionic crystalssomewhat similar to metallic crystalsOne ion forms, for example, a uniform cellThe second ion fits in between the first ionWhat is the learning point ofharping on lead examples?Cl-Is this lithium or chloride?How did you know?What happens when the cation size is increased?Face Centered Cubic Cl StructureBody CenteredCubic Cl StructureFace centeredcubicBody Centered CubicCl-Chloride adopts auniform structureand the smallerLi fits in betweento satisfy thecharge.Cl-Chloride adopts the samestructure as for Lithium chloridebut the cell is larger because ofmovement to accommodate thelarger Sodium cation.Cl-Cesium is so large thatthe same structure cannot be adopted bychloride22
A warning: have to account for all the atoms and their individualUnit cellsIonic Bonds: Collection of Interactions (kJ/mol)LiF – 1017LiCl – 828LiBr – 787LiI -737 657600ClEasy to “see” fccFcc 4 atoms(625 -1550)What “rules” apply here?How about for Na ?Cl- fcc1 wholeIn centerClCl-4 ¼ atoms at top4 ¼ atoms at bottomg d vold 1moleLiF 4(6.94) 4(19.0) 6.02 x10 23 atomsLiF moleLiF( 4moleculesLiF ) gg 2.65 3volcm 10 8 cm 4.02 A A 312 ¼ atoms 34 ¼ atoms at the “waist”Cl-Example: Determine the net number of Li and F- ions in theLiF unit cell, given that the structure is fcc (for both ions).Calculate its density given that s is 4.02A on a side.Fcc 4 for Li 4r s 2 Necessary?Fcc 4 for FTotal 8 ionsNoNa fccTotal atoms 4Fcc“A” students work(without solutions manual) 10 problems/night.Alanah FitchFlanner Hall 402508-3119afitch@luc.eduOffice Hours W – F 2-3 pmModule #12Intermolecular Forces23
Intermolecular Forces1. Evidence for Intermolecular Forces2. Phase Diagrams (briefly)3. Liquid-Vapor Equilibrium1. Kinetic theory2. Gas escape as a way to measure liquid intermolecular forces4. Boiling points related liquid Intermolecular Forces1. Dipole-dipole2. Dispersion3. H-bonding4. example application – heat capacity of lakes5. Solid Intermolecular Forces1. Molecular Solids (Dispersion/ H-bonding)2. Network Covalent (Covalent) – example glass3. Ionic solids (Ion/ion)4. Metallic solids (metal bonding)6. Structures of Crystals7. Summary slides1. Unit Cells2. Common Metal Unit cells1. Calculate density of lead3. Common Ionic Solid Unit cells1. Calculate density of ionic solidSummary SlideVapor pressure over a solution is related to the energy required toescape the solution: this ideal leads to the following equation P Hvaporization 11 ln 2 R P1 T2 T1 Summary SlideIonic Bonds: Collection ofInteractions (kJ/mol)LiF – 1017NaFLiCl – 828NaClLiBr – 787NaBrLiI -737 NaI682bond energy (kJ/mol)See also Table 8.2910788732(625 -1550)Covalent Bonds (kJ/mol)74-1000 Organic ChemistrySee also Table 8.4Also bioMetallic bonds 57600Environmental/GeologyNetwork forming co
Intermolecular Forces 1. Evidence for Intermolecular Forces 2. Phase Diagrams (briefly) 3. Liquid-Vapor Equilibrium 1. Kinetic theory 2. Gas escape as a way to measure liquid intermolecular forces 4. Boiling points related liquid Intermolecular Forces 1. Dipole-dipole 2. Dispersion 3. H-b
Mar 06, 2007 · intermolecular forces. Volatility-The more volatile, the weaker the intermolecular forces. Vapor pressure-The higher the vapor pressure, the weaker the intermolecular forces. The melting point/boiling point is higher in substances that have stronger intermolecular forces. Other physical properties include viscosity.File Size: 556KB
AP Chemistry Chapter 11. Intermolecular Forces, Liquids, and Solids - 1 - Chapter 11. Intermolecular Forces, Liquids, and Solids 11.2 Intermolecular Forces Intermolecular forces are much weaker than ionic or covalent bonds (e.g., 16 kJ/mol versus 431 kJ/mol for HCl). Melting o
Forces Jacob Israelachvili ch 3,4 L6 Interaction forces- II Binnig, Quate, Gerber (reader) Intermolecular & Surface Forces Jacob Israelachvili ch 4,5 L5 Interaction forces-III Intermolecular & Surface Forces Jacob Israelachvili ch 5,6 Interaction forces-IV Intermolecular & Surface Forces Jacob Israelachvili ch 6,7 L7 F-Z, F-d curves – I
intermolecular forces. Intermolecular Force (IMF): between molecules. This is the force that holds molecules together. It is a form of “stickiness” between molecules. Examples of intermolecular forces are London dispersion forces (LDF), dipole-dipole forces (DDF), and hydrogen bridging forces (HBF).File Size: 832KB
Intermolecular Forces 11.2 Intermolecular forces are attractive forces between molecules. Intramolecular forces hold atoms together in a molecule. Intermolecular vs Intramolecular 41 kJ to vaporize 1 mole of water (inter) 930 kJ to break all O-H bonds in 1 mole of water (intra) Generally,
Molecules have the highest kinetic energy in which state? Slide 20 / 136 Intermolecular Forces Intermolecular forces are electrostatic forces of attraction or repulsion that exists between molecules. The attractions between molecules, intermolecular forces, are not nearly as strong as the intramolecular
Summary for intermolecular forces Chapter 12 Section 12.3 Intermolecular Forces ¾Relative ranking intermolecular forces .which is the strongest force, which is the weakest force? Chapter 12 3.1 Impact of IMF ¾The relative strengths of IMF help explain . ¾Physical states of matter
panied by legal questions.2 We believe that our modern high-technology era will be faced by an unusual number of such questions growing out of what we will undoubtedly term, “artificial intelligence” (“AI”), but which in fact is the combination of advanced algorithms, important pools of data, usually referred to as “big data,” and the many technol-ogies that exploit these. Some .
