1. CHAPTER 12 CHEMISTRY

2. A comparison of Liquids & Solids  Molecular speed   Molecular distance   Molecular “order”   Amount/Strength of Bonds  Liquids are faster Liquids are closer than gases, farther than solids Solids – most order; liquids - less order; gases – least order Solids have the strongest external bonds

3. LIQUIDS  Indefinite shape   Definite volume   Not very compressible   Fluid   Ability to diffuse  Takes shape of container Volume will change only slightly – with pressure or temp changes Particles are more closely packed together Particles can “flow” – can glide past one another Constant random motion – slower than gases; Increase temp = Increase diffusion

4. LIQUIDS  Surface Tension A force that tends to pull adjacent parts of a liquid’s surface TOGETHER & DOWNWARD, thus making the surface less penetrable by solid bodies

5. LIQUIDS  How many pennies can you fit into a cup full of water? (Regular water only!)  How many drops of water can you fit on the surface of a penny?  Can you float a paper clip? Use: Regular water Soap water Salt water

6. LIQUIDS  Ability to vaporize  Ability to solidify Vaporization; liq  gas; Two ways this can happen: BOILING, EVAPORATION Becoming a solid; liq  solids; Forces hold particles together in a solid

7. SOLIDS  Can be: Crystalline Crystalline Amorphous Amorphous Consists of crystals Particles are arranged in an ORDERLY, GEOMETRIC, REPEATING pattern Particles are arranged RANDOMLY Ex – glass, plastic http://www.cartage.org.lb/en/themes/sciences/Physics/SolidStatePhysics/Ato micBonding/BondingMechanisms/Difference/Difference.htm

8. SOLIDS  Definite shape   Definite volume   NOT fluid   Not compressible  Forces hold particles together Particles packed very close together Particles held in fixed positions Very little empty space between particles

9. SOLIDS  Extremely SLOW diffusion   High density   Ability to melt  Strong attractive forces – don’t mix on own Particles packed very close – high mass, low volume KE overcomes intermolecular forces; sol  liq

10. CRYSTALLINE SOLIDS   4 Types: Ionic Crystalline Solids Covalent Networks Metallics Covalent Moleculars No surprises – you WILL have to list and explain these 4 on the test!!

11. CRYSTALLINE SOLIDS  Ionic Crystalline Solids Transfer of electrons, +-+-+- (metal + nonmetal) Transfer of electrons, +-+-+- (metal + nonmetal) Crystal Lattice Crystal Lattice Total 3D array of points that describe the arrangement of particles in a crystalTotal 3D array of points that describe the arrangement of particles in a crystal Unit Cell Unit Cell Smallest portion of a crystal lattice that reveals the 3D patternSmallest portion of a crystal lattice that reveals the 3D pattern There are a total of 7 different shapes (crystallography)There are a total of 7 different shapes (crystallography) http://chemed.chem.wisc.edu/chempaths/GenChem- Textbook/Lattices-and-Unit-Cells-837.htmlhttp://chemed.chem.wisc.edu/chempaths/GenChem- Textbook/Lattices-and-Unit-Cells-837.htmlhttp://chemed.chem.wisc.edu/chempaths/GenChem- Textbook/Lattices-and-Unit-Cells-837.htmlhttp://chemed.chem.wisc.edu/chempaths/GenChem- Textbook/Lattices-and-Unit-Cells-837.html http://www.chem.ubc.ca/courseware/121/tutorials/exp7A/2.ht mlhttp://www.chem.ubc.ca/courseware/121/tutorials/exp7A/2.ht mlhttp://www.chem.ubc.ca/courseware/121/tutorials/exp7A/2.ht mlhttp://www.chem.ubc.ca/courseware/121/tutorials/exp7A/2.ht ml

12. Crystalline Solids  Examples Cubic Cubic 90° angles90° angles L=w=hL=w=h Tetragonal Tetragonal 90° angles90° angles Longer sides (rectangle) than top or bottom (square)Longer sides (rectangle) than top or bottom (square) Orthorhombic Orthorhombic 90° angles90° angles l≠w≠hl≠w≠h ALL rectangular sides!ALL rectangular sides!

13. Crystalline Solids  Covalent Networks Single atoms covalently bonded to its nearest neighboring atom Single atoms covalently bonded to its nearest neighboring atom Examples: Examples: Diamond (True Covalent Network)Diamond (True Covalent Network) Graphite (Planar Network)Graphite (Planar Network) C 60 (Buckyball)C 60 (Buckyball) No surprises – you WILL have to list and explain these 3 on the test!

14. True Covalent Networks  Hard  Interlocking networks  High MP, non- or semiconductors  Strong http://cheminfo.chem.ou.edu/~mra/jmol/jmol.php

15. Planar Network  “Molecular Sheets”  Weak intermolecular forces between sheets  Sheets glide past one another and allow a thin deposit of graphite as you write http://cheminfo.chem.ou.edu/~mra/jmol/jmol.php

16. Buckyball  “Soccer ball”  32 faces – 20 hexagons and 12 pentagons

17. Metallics  Positive ions of metals surrounded by valence electrons  High electric conductivity due to the freedom of electrons to move

18. Covalent Molecular  Covalently bonded molecules held together by intermolecular forces  Low MP, easily vaporized, soft, good insulators  Example - ice

19. Summary  http://www.chm.davidson.edu/ChemistryA pplets/Crystals/NetworkSolids.html http://www.chm.davidson.edu/ChemistryA pplets/Crystals/NetworkSolids.html http://www.chm.davidson.edu/ChemistryA pplets/Crystals/NetworkSolids.html

20. Amorphous Solid  Noncrystalline solids  NO regular, natural shape Takes on shape imposed on them Takes on shape imposed on them Particles arranged randomly Particles arranged randomly  Examples: Rubber, glass, plastic Rubber, glass, plastic

21. Changes of State  Equilibrium Two opposing changes occur at equal rates Two opposing changes occur at equal rates  LeChatlier’s Principle Add a stress (change in concentration, change in pressure, change in temperature) to a system and the system will work to relieve the stress Add a stress (change in concentration, change in pressure, change in temperature) to a system and the system will work to relieve the stress RULES – RULES – Shift away from an added substance, towards removed substance (Solids do not affect concentration!!)Shift away from an added substance, towards removed substance (Solids do not affect concentration!!) Treat energy as a reactant/product for changes in tempTreat energy as a reactant/product for changes in temp If decrease volume – shift towards side with fewer gas moleculesIf decrease volume – shift towards side with fewer gas molecules

22. LeChatlier’s Principle

23.  Example: As 4 O 6 (s) + 6C(s)  As 4 (g) + 6CO(g) As 4 O 6 (s) + 6C(s)  As 4 (g) + 6CO(g) How would this shift if?How would this shift if? Add CO Add CO Remove As 4 O 6 Remove As 4 O 6 Remove As 4 Remove As 4 N 2 (g) + 3H 2 (g)  2NH 3 (g) N 2 (g) + 3H 2 (g)  2NH 3 (g) How would this shift if?How would this shift if? Decrease volume Decrease volume CaCO 3 (s) + energy  CaO(s) + CO 2 (g) CaCO 3 (s) + energy  CaO(s) + CO 2 (g) How would this shift if?How would this shift if? Increase temperature Increase temperature Decrease temperature Decrease temperature

24. Boiling  Conversion of a liquid to a vapor  VAPOR PRESSURE Pressure of the vapor (gas) above the liquid surface Pressure of the vapor (gas) above the liquid surface Boiling occurs when VP = P atm (Barometer reading) Boiling occurs when VP = P atm (Barometer reading)  If P atm low … (for ex - on top of a mountain) Boiling occurs easier…low BP Boiling occurs easier…low BP Boiling Point of water on top of Mt. Everest = 69°CBoiling Point of water on top of Mt. Everest = 69°C Food takes longer to cook (because it at cooking at a low temp!) Food takes longer to cook (because it at cooking at a low temp!)  If P atm high… (for ex – below sea level) Boiling is difficult…high BP Boiling is difficult…high BP Boiling point of water at 1000ft below sea level = 101.1°CBoiling point of water at 1000ft below sea level = 101.1°C Food cooks faster (because it is cooking at a high temp!) Food cooks faster (because it is cooking at a high temp!)

25. Boiling  Normal Boiling Point Boiling point at standard atmospheric pressure (1 atm, 760 mmHg, etc) – Sea Level Boiling point at standard atmospheric pressure (1 atm, 760 mmHg, etc) – Sea Level

26. Melting/Freezing  Normal MP/FP of water = 0°C (NOT affected by pressure changes!!)  Sublimation Solid  gas Solid  gas Some substance do this at room temperature Some substance do this at room temperature Example – dry ice (solid CO 2 )Example – dry ice (solid CO 2 )

27. Heating/Cooling Curves Heating Curve:

28. Heating/Cooling Curve Cooling curve would be reversed:

29. Phase Diagram  Water: Lecture Lecture

30. Phase Diagram  Carbon Dioxide

31. Phase Diagram  Triple Point All three states of matter exist simultaneously All three states of matter exist simultaneously  Critical Point Last temp and pressure at which a liquid can exist Last temp and pressure at which a liquid can exist  Difference between phase diagram of water and carbon dioxide?

32. Water  Liquid water Has “clumps” of 4-8 molecules per groupHas “clumps” of 4-8 molecules per group  Solid water Forms hexagonal lattice (6 sides) with empty spacesForms hexagonal lattice (6 sides) with empty spaces Gives solid ice low density (large volume, small mass)Gives solid ice low density (large volume, small mass) Solid floats on liquid!!Solid floats on liquid!!Solid floats on liquid!!Solid floats on liquid!!