1. Liquids and Solids

2. Characteristics of Liquids and Solids What properties allow you to classify a substance as a solid, liquid, or gas?

3. PropertySolidLiquidGas Volume Shape Relative density Compressibility Fluid? Space between particles Diffusion rate Motion of particles (amount and type) Forces between particles?

4. Surface Tension Surface tension is the tendency for liquid surface to contract. Depends on IMFs Compounds that interfere with the IMFs and reduce surface tension are called surfactants.

5. Figure 12.18 The molecular basis of surface tension. hydrogen bonding occurs in three dimensions hydrogen bonding occurs across the surface and below the surface the net vector for attractive forces is downward

6. Figure 12.19 Shape of water or mercury meniscus in glass. adhesive forces stronger cohesive forces H2OH2O capillarity Hg

7. Figure 12.4 Liquid-gas equilibrium.

8. Figure 12.6 Vapor pressure as a function of temperature and intermolecular forces. Vapor pressure = the pressure of the vapor resulting from evaporation of a liquid (or solid) above a sample of the liquid (or solid) in a closed container What factors affect the vapor pressure? Vapor Pressure

9. Boiling Point Temperature at which the vapor pressure of the liquid = atmospheric pressure Normal boiling point vp liquid = 760 mmHg condensing point = boiling point

10. What if…? You are camping at a high altitude of 10,000 ft where the atmospheric pressure is 535 mmHg. If you boil an egg for 10 minutes will it be hard-boiled just right, overdone, or runny? Explain your choice.

11. Subliming Point Temperature at which the vapor pressure of the solid equals atmospheric pressure Depositing point = subliming point Iodine subliming

12. Figure 12.12 Dipole moment and boiling point.

13. Figure 12.13 Hydrogen bonding and boiling point.

14. Figure 12.16 Molecular shape and boiling point. more points for dispersion forces to act fewer points for dispersion forces to act

15. Freezing Point Temperature at which liquid and solid are in equilibrium Not affected by pressure but does depend on IMFs and molar mass Melting point = freezing point

16. Figure 12.21 The hexagonal structure of ice.

17. Figure 12.22 The striking beauty of crystalline solids.

18. portion of a 3-D lattice Figure 12.23 The crystal lattice and the unit cell. lattice point unit cell portion of a 2-D lattice unit cell

19. Figure 12.27 Diffraction of x-rays by crystal planes.

20. Table 12.5 Characteristics of the Major Types of Crystalline Solids Particles Interparticle Forces Physical Behavior Examples (mp, 0 C) Atomic Molecular Ionic Metallic Network Group 8A(18) [Ne-249 to Rn-71] Molecules Positive & negative ions Atoms Soft, very low mp, poor thermal & electrical conductors DispersionAtoms Dispersion, dipole-dipole, H bonds Fairly soft, low to moderate mp, poor thermal & electrical conductors Nonpolar - O 2 [-219], C 4 H 10 [-138], Cl 2 [-101], C 6 H 14 [-95] Polar - SO 2 [-73], CHCl 3 [-64], HNO 3 [- 42], H 2 O[0.0] Covalent bond Metallic bond Ion-ion attraction Very hard, very high mp, usually poor thermal and electrical conductors Soft to hard, low to very high mp, excellent thermal and electrical conductors, malleable and ductile Hard & brittle, high mp, good thermal & electrical conductors when molten NaCl [801] CaF 2 [1423] MgO [2852] Na [97.8] Zn [420] Fe [1535]