Solids & Liquids

1. Solids & Liquids • I. IMF – intermolecular forces -Attractive forces betweenmolecules. • A. Much weaker than chemical bonds within molecules.

3. London forces & Dipole-Dipole forces: View animation online. • Hydrogen bonds

4. II. Liquids – fluid (ability to flow) definite volume, takes the shape of its container • A. Properties & kinetic molecular theory – molecules in constant random motion, much less KE than gases & molecules are closer together

5. 1. density – d = mass/vol compared to gases density is much greater • 2. incompressibility – much less commpressiblethan gases • 3. ability to diffuse – can diffuse but not as fast as gases because liquid molecules are closer together & the IMF are much greater

6. 4. surface tension – force that pulls adjacent particles at the surface of a liquid together – causes liquids to “bead” • a. water has a much higher surface tension than most other liquids

7. And 1 more! • water strider • A tiny water walking machine/robot Image Credit: Environmental Graffiti

8. b. capillary action – attraction of a surface of a liquid to the surface of a solid – causes meniscus • water mercury (surface tension stronger than capillary action)

9. 5. evaporation – particles escaping from the surface of a non-boiling liquid into gas state • a. vaporization – phase change of liquid to gas or solid to gas phase change • 6. boiling – change liquid to gas by adding heat E – change happens through out liquid not just at the surface • liquid + heat gas (endothermic)

10. 7. freezing – phase change of liquid to solid by removing heat E • Liquid solid + heat (exothermic)

12. III. Solids- definite shape & volume • A. Properties & kinetic molecular theory-(IMF stronger) molecules are in a fixed, vibrating position • 1. definite shape & vol • a. crystalline solids – made of crystals • 1) crystal – particles arranged in an orderly, repeating, geometric pattern

13. b. amorphous solid – particles are arranged randomly

14. 2. Definite melting point – temp at which a solid becomes liquid • a. melting – physical change from solid to liquid solid + heat→ liquid (endothermic) • b.supercooled liquids – substances that retain certain liquid properties even when at a temp where they appear solid --- glass, plastics

15. 3. Density & incompressibility – more dense than gases & liquids, least comp. • D = mass ÷ volume • 4. Diffusion – can occur but at an incredibly slooooowrate (for practical purposes we can say that it doesn’t diffuse

16. B. Crystalline Solids • 1. crystal structure- 3-D arrangement of particles in a crystal • 2. unit cell – smallest part of a crystal that shows the 3-D arrangement of the crystal

17. 3. binding forces in crystals • a. covalent network – made of single atoms, each are covalently bonded to its nearest neighbor, hard, brittle, nonconductor or semiconductor (diamond, quartz, graphite)

18. b. metallic crystal – metal atoms surrounded by a sea of electrons,good conductor, malleable…. • . ionic crystals – made of + & - ions arranged in a regular pattern, hard, brittle, ↑mp, good insulator

19. d. covalent molecule – covalently bonded molecules held together by IMF, ↓ mp, soft, good insulator, easily vaporized, polar cov. more strongly held together than nonpolarcov. • covalent network • Metallic decreasing • m.p. melting point • ionic • polar covalent • covalent molecular