Intermolecular Forces: Liquids, and SolidsSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Chapter 13 1Intermolecular Forces: Intermolecular Forces: Liquids, and SolidsLiquids, and SolidsChapter 13Chapter 13Chapter 13 2A Molecular Comparison of Liquids and A Molecular Comparison of Liquids and SolidsSolidsChapter 13 3Intermolecular ForcesIntermolecular ForcesChapter 13 4Intermolecular ForcesIntermolecular ForcesIon-Dipole ForcesIon-Dipole Forces-Interaction between an ion (Na+) and a dipole (water).-Strongest of all intermolecular forcesChapter 13 5Intermolecular ForcesIntermolecular ForcesChapter 13 6Intermolecular ForcesIntermolecular ForcesDipole-Dipole ForcesDipole-Dipole Forces-Interaction between an dipole on one molecule and a dipole on an adjacent molecule.-Dipole-dipole forces exist between neutral polar molecules.-Weaker than ion-dipole forcesChapter 13 7Intermolecular ForcesIntermolecular ForcesChapter 13 8Intermolecular ForcesIntermolecular ForcesLondon Dispersion ForcesLondon Dispersion ForcesInduced Dipole – Induced DipoleInduced Dipole – Induced Dipole-Weakest of all intermolecular forces.-It is possible for two adjacent nonpolar molecules to affect each other.-The nucleus of one molecule (or atom) attracts the electrons of the adjacent molecule (or atom).-This attraction causes the electron clouds become distorted.-In that instant a polar molecule (dipole) is formed (called an instantaneous dipole).Chapter 13 9Intermolecular ForcesIntermolecular ForcesLondon Dispersion ForcesLondon Dispersion ForcesChapter 13 10Intermolecular ForcesIntermolecular ForcesHydrogen BondingHydrogen Bonding-A special case of dipole-dipole forces.-This intermolecular force is very strong. -Strongest of the three Van der Waal’s forces (Hydrogen bonding, Dipole-dipole, London forces,)-H-bonding requires H bonded to an electronegative element (most important for compounds of F, O, and N).Chapter 13 11Intermolecular ForcesIntermolecular ForcesHydrogen BondingHydrogen BondingChapter 13 12Some Properties of LiquidsSome Properties of LiquidsViscosityViscosity-Viscosity is the resistance of a liquid to flow.-A liquid flows by sliding molecules over each other.-The stronger the intermolecular forces, the higher the viscosity.Chapter 13 13Some Properties of LiquidsSome Properties of LiquidsSurface TensionSurface Tension-The surface of a liquid behaves as a membrane or barrier.-This is due to the unequal attractive forces on molecules as the surface.-Surface molecules are only attracted inwards towards the bulk molecules.Chapter 13 14Some Properties of LiquidsSome Properties of LiquidsSurface TensionSurface Tension-Cohesive forces bind molecules to each other.-Adhesive forces bind molecules to a surface.Chapter 13 15Some Properties of LiquidsSome Properties of LiquidsSurface TensionSurface Tension-Meniscus is the shape of the liquid surface. –If adhesive forces are greater than cohesive forces, the liquid surface is attracted to its container more than the bulk molecules. Therefore, the meniscus is U-shaped (e.g. water in glass).–If cohesive forces are greater than adhesive forces, the meniscus is curved downwards.Chapter 13 16Some Properties of LiquidsSome Properties of LiquidsSurface TensionSurface TensionCapillary Action - When a narrow glass tube is placed in water, the meniscus pulls the water up the tube.Chapter 13 17Properties of LiquidsProperties of LiquidsVaporizationVaporization•Also called evaporation–A process in which a substance is transfromed from a liquid to a gas.•Standard molar enthalpy of vaporization (Hovap)–The energy required to convert one mole of a liquid at its boiling point to a gas.•The resulting gas will exert a pressure on a system.Chapter 13 18Properties of LiquidsProperties of LiquidsVapor PressureVapor Pressure•This is the pressure exerted by a substance in the gas phase.•As a liquid’s temperature increases, its vapor pressure increases.Chapter 13 19Properties of LiquidsProperties of LiquidsVapor PressureVapor PressureVolatile – A substance which has a low boiling pointOrA substance which has a high vapor pressure at a low temperatureChapter 13 20Properties of LiquidsProperties of LiquidsVapor Pressure and Boiling PointVapor Pressure and Boiling Point-Liquids boil when the external pressure equals the vapor pressure.-Two ways to get a liquid to boil: increase temperature or decrease pressure.-Normal boiling point is the boiling point at 760 mmHg (1 atm).Chapter 13 21Properties of LiquidsProperties of LiquidsVapor Pressure and Boiling PointVapor Pressure and Boiling Point-Vapor pressure, temperature and enthalpy of vaporization can be related to each other using:Clausius-Clapeyron equation:211211lnTTRHPPovapP = pressureT = temperatureR = gas lawHovap = enthalpy of vaporizationChapter 13 22Properties of LiquidsProperties of LiquidsVapor Pressure and Boiling PointVapor Pressure and Boiling PointThe Clausius-Clapeyron equation makes more sense when it is rearranged into the slope intercept form.CRTHPovaplnChapter 13 23Properties of LiquidsProperties of LiquidsVapor Pressure and Boiling PointVapor Pressure and Boiling PointChapter 13 24Structures of SolidsStructures of SolidsUnit CellsUnit Cells-Crystalline solid: well-ordered, definite arrangements of molecules, atoms or ions. -Crystals have an ordered, repeated structure.-The smallest repeating unit in a crystal is a unit cell.-Three-dimensional stacking of unit cells is the crystal lattice.Chapter 13 25Structures of SolidsStructures of SolidsUnit CellsUnit CellsChapter 13 26Structures of SolidsStructures of SolidsUnit CellsUnit CellsChapter 13 27Structures of SolidsStructures of SolidsCell OccupancyCell OccupancyChapter 13 28Structures of SolidsStructures of SolidsCell OccupancyCell OccupancyChapter 13 29Structures of SolidsStructures of SolidsCell OccupancyCell OccupancySite OccupancyCorner 1/8Edge 1/4Face 1/2Center 1Chapter 13 30Structures of SolidsStructures of SolidsCell OccupancyCell OccupancyZinc (grey) 4 Center 4 atomsSulfur (yellow) 8 corners6 faces1 atom3 atomsZn4S4  ZnSChapter 13 31Structures of SolidsStructures of SolidsClose Packing of