1. Solids Chapter 12.2 Objectives: Describe the motion of particles in solids and the properties of solids according to the kinetic-molecular theory. Distinguish between the two types of solids. Describe the different types of crystal symmetry. Define crystal structure and unit cell.

2. Properties of Solids and Kinetic-Molecular Theory Particles are more closely packed. Intermolecular forces are much more effective in solids. Hold molecules in fixed position, only vibration movement More ordered than other phases Two types of Solids Crystalline solids: Consist of crystals, which are, a substance in which the particles are arranged in an orderly, geometric, repeating pattern. Amorphous solid: Solids whose particles are arranged randomly Ex: glass and plastic

4. Physical change of a solid to a liquid by the addition of heat. (Temperature which a solid becomes a liquid)

5. Kinetic energy of particles overcome attractive forces holding them together.

6. Supercooled Liquids

10. Ions – monatomic or polyatomic

11. Form when

12. Group 1 or 2 metals combine with group 16 or 17 nonmetals

13. Hard and brittle

14. High melting point

16. Examples: diamond, Quartz,

17. diamond, Quartz, silicon carbide

18. Very hard and brittle

19. Rather high melting points

21. Hard and malleable

22. High conductivity

24. Examples: Nonpolar

25. Hydrogen, methane, benzene

26. Weak London dispersion forces

27. Examples: Polar

28. Water, ammonia

29. Hydrogen bonding, stronger dipole-dipole forces

30. LOW melting points

31. Easily vaporized

32. Relatively soft