1. Liquids and Solids 1. To learn about dipole-dipole, hydrogen bonding and London dispersion forces 2. To understand the effect of intermolecular forces on the properties of liquids 3. To learn some of the important features of water 4. To learn about interactions among water molecules 5. To understand and use heat of fusion and heat of vaporization Objectives 14.1 Intermolecular Forces and Phase Changes

2. Liquids and Solids Matter can be described by its physical properties. The physical properties of a substance generally depend on the spacing between particles (atoms, molecules, ions) that make up the substance and the forces of attraction among them. A. Intermolecular Forces

3. Liquids and Solids Forces of attraction between particles (including the noble gases and also different parts of some large molecules) are important in determining many macroscopic properties of a substance, including how the observable physical state changes with temperature. A. Intermolecular Forces

4. Liquids and Solids A. Intermolecular Forces Low density Highly compressible Fill container Reviewing what we know GasesSolids High density Slightly compressible Rigid (keeps its shape)

5. Liquids and Solids A. Intermolecular Forces Intermolecular forces – occur between molecules Intramolecular forces – occur inside the molecules

6. Liquids and Solids A. Intermolecular Forces Dipole – dipole attraction

7. Liquids and Solids A. Intermolecular Forces Occurs between H and highly electronegative atom (for example N, O, F) Hydrogen Bonding

8. Liquids and Solids A. Intermolecular Forces Affects physical properties Boiling point Hydrogen Bonding

9. Liquids and Solids A. Intermolecular Forces Formation of instantaneous dipoles London Dispersion Forces

10. Liquids and Solids A. Intermolecular Forces Nonpolar molecules London Dispersion Forces

11. Liquids and Solids A. Intermolecular Forces Become stronger as the sizes of atoms or molecules increase London Dispersion Forces

12. Liquids and Solids B. Water and Its Phase Changes Heating/cooling curve

13. Liquids and Solids B. Water and Its Phase Changes Normal boiling point – at 1 atm = 100 o C Normal freezing point – at 1 atm = 0 o C Density –Liquid water = 1.00 g/mL –Ice = 0.917 g/mL

14. Liquids and Solids C. Energy Requirements for the Changes of State Changes of state are physical changes No chemical bonds are broken

15. Liquids and Solids C. Energy Requirements for the Changes of State Molar heat of fusion – energy required to melt 1 mol of a substance Molar heat of vaporization – energy required to change 1 mol of a liquid to its vapor

16. Liquids and Solids 1. To understand the relationship among vaporization, condensation and vapor pressure 2. To relate the boiling point of water to its vapor pressure Objectives 14.2 Vapor Pressure and Boiling Point

17. Liquids and Solids A. Evaporation and Vapor Pressure Vaporization or evaporation Endothermic

18. Liquids and Solids A. Evaporation and Vapor Pressure Amount of liquid first decreases then becomes constant Condensation - process by which vapor molecules convert to a liquid When no further change is visible the opposing processes balance each other - equilibrium Vapor Pressure

19. Liquids and Solids A. Evaporation and Vapor Pressure Vapor pressure - pressure of the vapor present at equilibrium with its liquid Vapor Pressure –Vapor pressures vary widely - relates to intermolecular forces

20. Liquids and Solids B. Boiling Point and Vapor Pressure

21. Liquids and Solids B. Boiling Point and Vapor Pressure

22. Liquids and Solids 1. To learn about the types of crystalline solids 2. To understand the interparticle forces in crystalline solids 3. To learn how the bonding in metals determines metallic properties Objectives 14.3 Properties of Solids

23. Liquids and Solids Solids The type of bonding in the solid state can be deduced from the properties of the solid state.

24. Liquids and Solids A. The Solid State: Types of Solids Crystalline solids

25. Liquids and Solids A. The Solid State: Types of Solids

26. Liquids and Solids A. The Solid State: Types of Solids

27. Liquids and Solids B. Bonding in Solids

28. Liquids and Solids B. Bonding in Solids Stable substances with high melting points Held together by strong forces between ions Ionic Solids

29. Liquids and Solids B. Bonding in Solids Fundamental particle is a molecule Melt at relatively low temperatures Held together by weak intermolecular forces Molecular Solids

30. Liquids and Solids B. Bonding in Solids Fundamental particle is the atom Properties vary greatly Group 8 - low melting points Diamond - very high melting point Atomic Solids

31. Liquids and Solids B. Bonding in Solids Metals are held together by nondirectional covalent bonds (called the electron sea model) among the closely packed atoms Bonding in Metals

32. Liquids and Solids B. Bonding in Solids Metals form alloys of two types Bonding in Metals –Substitutional – different atoms are substituted for the host metal atoms

33. Liquids and Solids B. Bonding in Solids Metals form alloys of two types Bonding in Metals –Interstitial – small atoms are introduced into the “holes” in the metallic structure