1. Chapter 51 Example NO 2 ( ) nitrogen ( ) oxide 2 O’snitrogen dioxide 1 NMononitrogen dioxide often omit “mono” Nitrogen dioxide

2. Chapter 52 Name the following: CCl 4 N 2 O 3 SiS 2

3. Chapter 53 Name the following: CCl 4 carbon tetrachloride N 2 O 3 dinitrogen trioxide SiS 2 silicon disulfide

4. Chapter 54 Write the formula for dihydrogen monoxide Silicon tetrafluoride dinitrogentetroxide

5. Chapter 55 Write the formula for dihydrogen monoxideH 2 O Silicon tetrafluorideSiF 4 dinitrogen tetroxideN 2 O 4

6. Chapter 56 Lewis Dot Structures Helpful in determining 3-D Shape of molecule Can use 3-D shape to predict properties of molecules

7. Chapter 57 Rules for Lewis structures for molecules 1.Put in the atoms and arrange them to show which atoms are connected to which other atoms. H always on outside 2.Count the total number of outer shell electrons available to form bonds. Each atom contributes its group # of e-

8. Chapter 58 3.Draw bonds between atoms. Add in the remaining available electrons in pairs, starting with outside atoms to make octets 4.Make double or triple bonds if necessary to form complete octets around each atom. (Move e - pairs) Exceptions to full octet H needs only 2 e - B needs only 6 e - Period 3 or higher can have > 8

9. Chapter 59 Double check to make sure all atoms have full octets!!!

10. Chapter 510 Draw Lewis structures for: H 2 HCl PH 3 CO 2

11. Chapter 511 Resonance Some compounds can have “equivalent” resonance structures (SO 2 ) Only difference is “placement” of double bond Two structures are known as resonance forms

12. Chapter 512 In actual fact, neither double bond structure exists True situation is resonance hybrid (midway between two resonance structures)

13. Chapter 513 Types of Covalent Bonds Bond TypePairs of e - Total electrons Single 12 Double24 Triple 36 Unshared pairs of electrons are known as non-bonding pairs or lone pairs

14. Chapter 514 Bond Energy Bond energy is amount of energy required to break a bond Bond energies measured in J or kJ Stronger bonds have higher bond energy Triple > Double > Single

15. Chapter 515 Bond Length Bond length is distance between two nuclei Shorter in multiple bonds Length of Bond: Triple < Double < Single

16. Chapter 516 Valence Shell Electron Pair Repulsion (VSEPR) Electron “pair” groups in the outer shell of atoms arrange themselves as far away from each other as possible. Electron group occupies one region of space: bonding pair of electrons nonbonding pair of electrons (lone pair) double or triple bond

17. Chapter 517 Molecular Geometry Arrangement of atoms around a central atom Look at one center at a time

18. Chapter 518 Central atom with: Two bonding regions (attached to two atoms) No lone (nonbonding) pairs Arrangement is linear Bond angles are 180 o

19. Chapter 519

20. Chapter 520 Central atom with: Three bonding regions (attached to three atoms) No lone (nonbonding) pairs Arrangement is planar (molecule is flat) Bond angles are 120 o

21. Chapter 521

22. Chapter 522 Central atom with: Four bonding regions (attached to four atoms) No lone (nonbonding) pairs Arrangement is tetrahedral Bond angles are 109.5 o

23. Chapter 523

24. Chapter 524 Representing 3-D Structures Solid line: bonds in plane of paper Dotted wedges: bonds that project behind (or beneath) the plane Solid wedges: bonds that project in front of (or above) the plane

25. Chapter 525

26. Chapter 526 Geometry of Atoms with Lone Pairs Two bonding regions (attached to two atoms) One lone (nonbonding) pair Arrangement is angular (bent) (molecule is flat) Bond angles are 120 o

27. Chapter 527

28. Chapter 528 Geometry of Atoms with Lone Pairs Three bonding regions (attached to three atoms) One lone (nonbonding) pair Arrangement is trigonal pyramidal Bond angles are 107 o

29. Chapter 529

30. Chapter 530 Geometry of Atoms with Lone Pairs Two bonding regions (attached to two atoms) Two lone (nonbonding) pairs Arrangement is angular (bent) Bond angles are 104.5 o

31. Chapter 531 Why are bond angles smaller than 109.5 o ? Bonding electrons have an atom on both sides of the bond Lone pairs tend to spread and force the bonding pairs closer together

32. Chapter 532

33. Chapter 533 Fig. 4.8

34. Chapter 534 Fig. 4.9

35. Chapter 535 Summary of Effects of Lone Pairs on Bond Angles

36. Chapter 536 Summary of Molecular Geometry # ElectronLoneBond AngleShape regionspairs 2 0180 o Linear 3 0120 o Planar 2 1Angular (bent) 4 0109.5 o Tetrahedral 3 1Trigonal pyramidal 2 2Angular (bent)

37. Chapter 537 Review: Electronegativity Measure of the relative pull of an atom on a shared pair of electrons Arbitrary scale ranging from 0 to 4 Most electronegative element is fluorine F has E = 4

38. Chapter 538 Electronegativity Values

39. Chapter 539 Polarity of bonds Covalent Bonds between atoms with similar electronegativity values are nonpolar Δ E < 0.5 Covalent Bonds between atoms with different electronegativity values are polar covalent 0.5 < Δ E < 1.9 Bonds between atoms with very different electronegativity values are ionic Δ E> 1.9

40. Chapter 540 Polar Bond has positive and negative ends to the bond (uneven distribution of charge) Polar molecule has positive and negative ends to the molecule (even distribution of charge)

41. Chapter 541 Polar Bond has positive and negative ends to the bond Polar molecule has positive and negative ends to the molecule Molecule acts like a dipole

42. Chapter 542 Polar Covalent Bonds--- Unequal Sharing of Electrons

43. Chapter 543 Dipoles can align in an electrical field Nonpolar molecules do not have +/- ends and do not align in electrical field

44. Chapter 544 Nonpolar molecule All of the bonds are C—H bonds. C end is slightly negative compared to H end for each bond Overall, molecule is nonpolar because it does not have positive and negative ends--- Polarities cancel out

45. Chapter 545 Polar Molecule Each O—H bond is polar O end is more negative than H end Negative end to molecule Polarities do not cancel each other----instead are additive

46. Chapter 546 Intramolecular Forces –Forces within molecules Covalent bonds Intermolecular Forces –Forces between molecules Hydrogen bonds Dipole-dipole interactions Dispersion Forces

47. Chapter 547 Intermolecular Forces Hold matter together Boiling point and melting point a good measure of how strong intermolecular forces are

48. Chapter 548 More energy is required to separate molecules held together by strong intermolecular forces than weak intermolecular forces. Materials with strong intermolecular forces have higher boiling points and melting points

49. Chapter 549 Ionic Forces Interaction between + and – charges on ions Strongest intermolecular forces –Found in salts –NaCl melts at 801 o C

50. Chapter 550 Hydrogen Bonds H that is covalently attached to O, N or F is attracted to a different O, N or F This attraction is a “hydrogen bond” Much weaker than ionic forces or covalent bonds (intramolecular bond) between atoms Important in biological systems Water melts at 0 o C

51. Chapter 551 Hydrogen Bond

52. Chapter 552 Dipole Forces Result from attraction between partially positive and partially negative ends (poles) of molecules Works only for polar molecules HCl melts at -112 o C

53. Chapter 553 Dipole Forces (a=solid, b=liquid)

54. Chapter 554 Dispersion Forces (London) Present in all molecules Weak temporary forces that result from movement of electrons within molecules and around atoms –Important in nonpolar materials –Each individual London force is very weak, but together they add up, especially for large molecules

55. Chapter 555 Intermolecular Forces Strongest Ionic forces (much stronger) Hydrogen bonding Dipole Forces Dispersion Forces Weakest

56. Chapter 556 Properties affected by Intermolecular Forces Melting points NaCl> H 2 O> HCl> CH 4 mp801 0 -112 -182.5 o C IonicH-bondDipoleLondon

57. Chapter 557 States of Matter Solid Liquid Gas

58. Chapter 558 States of Matter SolidLiquidGas Definite shape YesNo Definite volume Yes No Is fluid (Pours or Flows) NoYes

59. Chapter 559 SolidLiquidGas Interactions between Particles StrongModerateNone Particles touching YesYes (some holes) No Space between particles NoSome holes LOTS of space

60. Chapter 560 Changes of State Melting: Change from the solid to the liquid state Freezing: Change from the liquid to the solid state (solidification or crystallization)

61. Chapter 561 Changes of State Vaporization: Change from the liquid to the gaseous state (Evaporation or Boiling) Condensation: Change from the gaseous to the liquid state

62. Chapter 562 Changes of State Sublimation: Change from the solid to the gaseous state directly (skips liquid state) Deposition: Change from the gaseous to the solid state directly (skips liquid state)

63. Chapter 563 Melting point: Temperature at which substance goes from solid to liquid state Boiling point: Temperature at which substance goes from liquid to gaseous state

64. Chapter 564 Summary of State Changes

65. Chapter 565 Energy is needed to overcome the forces between molecules Need to add energy for substance to melt or vaporize (or sublime) Need to remove energy for substance to condense or freeze (or deposit) Heat of Vaporization is amount of energy needed to change given amount of liquid into gas at its boiling point

66. Chapter 566 Gases Lots of space between molecules Gas molecules can be pushed closer together because there is plenty of space between them Gases are compressible

67. Chapter 567 Molecules move in straight line until they hit the sides of their container and move in a different direction When molecules hit container, they exert a force Pressure: Force per unit area

68. Chapter 568 Pressure units Atmosphere: 1 atm is pressure at sea level mm Hg: 760 mm Hg is pressure at sea level 1 atm = 760 mm Hg

69. Chapter 569 Boyle’s Law Pressure (P) and Volume (V) of a gas are inversely proportional P α 1/V or PV = constant Raise Pressure → Lower Volume Lower Pressure → Increase Volume

70. Chapter 570

71. Chapter 571

72. Chapter 572 Charles’s Law Temperature (T) and Volume (V) of a gas are directly proportional P α T or P/T = constant Raise Temperature → Raise Volume Lower Temperature → Lower Volume

73. Chapter 573

74. Chapter 574 Solution is homogeneous mixture (mixed uniformly)

75. Chapter 575 Properties of Liquids Molecules are close together, so liquids are only slightly compressible Each liquid has a unique vapor pressure Vapor pressure is the pressure of gas molecules that have escaped the liquid state at a given temperature (closed container)

76. Chapter 576 Boiling Point Boiling Point: Temperature at which vapor pressure is equal to atmospheric pressure Normal Boiling Point: Boiling point at 1 atm pressure

77. Chapter 577 Water: Unique Properties Water is liquid at room temperature –Hydrogen bonds between water molecules give water a higher melting point Density of ice is less than density of water Water has high heat capacity. –Can absorb lots of energy with very little change in temperatue

78. Chapter 578 Hydrogen Bond

79. Chapter 579 Water: Unique Properties Water has high heat of vaporization Water has high surface tension Surface tension: Molecules at surface are only attracted on one side and form a “skin” Water is an excellent solvent

80. Chapter 580 Solutions Solvent: Substance present in greater amount Solute: Substance present in smaller amount Solubility: Amount of solute that will dissolve in a given amount of solvent at a given temperature

81. Chapter 581 Saturated solution: Contains the maximum amount of solute it can dissolve Unsaturated solution: Contains less than the maximum amount of solute possible (can dissolve more)

82. Chapter 582 Insoluble: Solute will not dissolve in the solvent Miscible: Solute and solvent will dissolve in all proportions

83. Chapter 583 Solubility Like dissolves like. Polar substances dissolve in polar substances Salt and water, sugar and water Nonpolar substances dissolve in nonpolar substances Grease and CCl 4 Unlike substances do not dissolve each other Oil and vinegar

84. Chapter 584 Ionic Compounds in Solution Ions dissolve in water---Charges on ions attracted to partial charges on polar water molecules

85. Chapter 585 Compounds in Solution Electrolyte: *Compound that conducts electricity when it is melted or dissolved in water *Ions carry charges and conduct electrons *Electrolytes are ionic compounds Non-electrolyte: *Compound that does not conduct electricity when it is melted or dissolved in water *Nonelectrolytes are not ionic compounds

86. Chapter 586 Strong electrolyte: *Completely separates into ions in solution *Conducts electricity well Weak electrolyte: *Partly separates into ions in solution *Conducts electricity poorly