1. Intermolecular Forces, Liquids and Solids
AP Notes Chapter 12 & 13
Intermolecular Forces, Liquids and Solids

2. 1. Ion - Ion

4. Dissociation Energy
Opposite of
Lattice Energy
MX (s)  M+(g) + X-(g)

5. 1. Ion - Ion
2. Ion - Permanent
Dipole

6. Hydrated Ions
A particle that is only weakly polar but is much larger than ion alone
The number of waters of hydration depends on size of ion and strength of charge to be stabilized (typically less than 5)

7. 1. Ion - Ion
2. Ion - Permanent
Dipole
3. Dipole - Dipole

8. Occurs between molecules with permanent dipoles (SO2 , CHCl3 , etc)

12. Hydrogen-Bonding
Relatively strong attraction between a hydrogen atom in one molecule and a highly electronegative atom (F, O, N) in a different molecule

13. Hydrogen-Bonding
Strong enough to produce a phase change in a compound that should be more random at that temperature (about 1.5 kJ)

15. Dimer of
Acetic Acid

16. Hydrogen-Bonding
How and why of bonding is not clear - most likely due to strong attraction between e- cloud of the highly EN atom and the nucleus of the H atom

17. QUESTION
Is the hydrogen bond a “true” chemical bond or is it just a very strong electrostatic attraction?

18. 1. Ion - Ion
2. Ion - Dipole
Dipole – Dipole
4. Dipole-Induced Dipole

20. 1. Ion - Ion
2. Ion - Dipole
Dipole – Dipole
4. Dipole-Induced Dipole
5. Dispersion Forces

21. Weakest of the intermolecular forces.
Dispersion Forces
Process of distorting an electron cloud by electrostatic forces of attraction and repulsion.
Weakest of the intermolecular forces.

22. Momentary attractions & repulsions Temporarydipoles established
Non-polar
molecules
Momentary attractions & repulsions
Temporarydipoles established

23. Dispersion forces also called
van der Waal’s forces

25. LIQUIDS & SOLIDS

26. various intermolecular forces holding a liquid together
Cohesive Forces
various intermolecular forces holding a liquid together

27. Vaporization
Process in which a substance in the liquid state becomes a gas.
Vaporization requires energy since it involves separation of particles that are attracted to one another.

28. Standard Molar Enthalpy of Vaporization, Hºvap
Energy required to convert one mole of liquid to one mole of the corresponding gas at the BP.
Always endothermic, Hvap is positive.
Liquids having greater attractive forces have higher Hvap

29. Condensation
Opposite of Evaporation
Condensation -- Exothermic

32. a measure of the resistance to flow of a liquid
Viscosity
a measure of the resistance to flow of a liquid
Ethylene Glycol & EtOH

33. the force that causes the surface of a liquid to contract
Surface Tension
the force that causes the surface of a liquid to contract

34. Paper Clip

35. the forces of attraction between a liquid and a surface
Adhesive Forces
the forces of attraction between a liquid and a surface

36. Capillary Action
Meniscus

37. SOLIDS

38. Amorphous Solids
Arrangement of particles lacks an ordered internal structure. As temp is lowered, molecules move slower and stop in somewhat random positions.

39. Atoms or ions are held in simple, regular geometric patterns
Crystalline Solids
Atoms or ions are held in simple, regular geometric patterns
Ionic
Molecular
Atomic

40. Atomic Solids
Noble Gases
Network
Metallic

46. X-ray Crystallography
How do you determine the spacing and position of atoms in an organized solid like a crystal?

47. X-ray Crystallography
Bragg discovered that nuclei of atoms or ions in a crystal will defract x-rays and form a pattern on photofilm that can be analyzed using simple trig & geometry

48. X-ray Crystallography
Use the fact that x-rays are part of the electromagnetic spectrum
Nuclei in crystalline solids are in layers that can act as a diffraction grating to the x-ray wavelength

49. Crystalline Solids
Diffract X-rays

51. Let D = “extra” distance that i’ must travel so that r’ is in-phase with r
D = xy + yz
or D = 2xy

52. Using trigonometry:

54. But for constructive interference

55. But for constructive interference
D = nl
nl = 2d sin q
BRAGG EQUATION

56. 1. X-rays from a copper
x-ray tube ( = 154 pm)
were diffracted at an
angle of by a
crystal of Si. What is
the interplanar spacing
in silicon?

57. Solids

58. Types of Solids
1. Atomic (Metals)
2. Molecular (Ice)
3. Ionic (NaCl)

59. Structures of Metals

60. The unit cell is the smallest representation of the building block of the regular lattice

61. Unit Cell Only 23 different unit cells have been defined
Called Brave’ Lattices
Patterns are determined by crystallography

62. CN is the number of atoms closest to any given atom in a crystal
Coordination Number CN is related to net atoms found within the unit cell
CN is the number of atoms closest to any given atom in a crystal

63. There are three Cubic Unit Cell Types
(pc) primitive cubic or simple cubic
(8 corners of cube) x (1/8 each corner in cell) = 1 net atom in cell
CN = 6
(bcc) body centered cubic
(1 atom in cube) +
[(8 corners of cube) x (1/8 each corner in cell)] = 2 net atoms in cell
CN = 8
(fcc) face centered cubic
[(6 faces of cube) x (1/2 of atom in cell)] +
[(8 corners of cube) x (1/8 each corner in cell)] = 4 net atoms in cell
or CN = 12
[(12 edges of cube) x (1/4 each edge in cell)] = 4 net atoms in cell
CN = 12

65. 1 Atom per Cell
CN = 6 l
l = 2r

66. 2 Atoms per Cell
CN = 8 l

67. 4 Atoms per Cell
CN = 12 l

68. Summary 2r Unit Cell Atoms Per Cell C.N. Length Of Side Cubic 1 6 BCC8
FCC 4 12

69. Primitive cubic
Face-centered cubic

70. Structures of Metals
Closest Packing

71. Structures of Metals
Closest Packing
1. Hexagonal
2. Cubic

72. A-B
A-B-C

73. (Primitive cubic)

74. 2. Al crystallizes as a face centered cube
2. Al crystallizes as a face centered cube. The atomic radius of Al is 143 pm. What is the density of Al in g/cm3?

75. 3. What is the percent of empty space in a body centered unit cell?

76. VAPOR
PRESSURE
Evaporation
and equilibrium

77. pressure in space above a liquid in a CLOSED container
Vapor Pressure
pressure in space above a liquid in a CLOSED container

81. PROPERTIES 1. closed container 2. temperature dependent
3. subject to all laws of partial pressures
4. dynamic system

82. temperature dependent
Vapor Pressure
temperature dependent P T

83. To plot in a linear fashion, must transform the variables.

84. ln P
1/T (K)

85. y = mx + b
& R = J/K mol

86. therefore:

87. define 2 points 1
ln P 2
1/T (K)

89. Subtract: ln P1 - ln P2

90. Clausius-Clapeyron Equation
Collect terms & factor:
Clausius-Clapeyron
Equation

91. SUMMARY OF IDEAS
TO BE CONSIDERED:
1. vapor pressure -
temperature dependent
2. volume determines time
needed to establish
vapor pressure -
NOT final pressure

92. 3. H (condensation) =
-H (vaporization)
4. Critical Point -
(T,P) above which vapor
cannot be liquefied
- regardless of pressure
5. Boiling: temperature
where vapor pressure
of liquid is the same as
atmospheric pressure

93. 4. The temperature inside a pressure cooker is 1150C
4. The temperature inside a pressure cooker is 1150C. What is the vapor pressure of water inside the pressure cooker?

94. PHASE
DIAGRAMS

95. PHASE DIAGRAM
A representation of the phases of a substance in a closed system as a function of temperature and pressure

96. Normal Boiling Point
Temperature at which the vapor pressure of the liquid is exactly 1 atmosphere

97. Normal Melting Point
Temperature at which the solid and liquid states have the same vapor pressure when the total P = 1 atm

98. Triple Point
The point on a phase diagram at which all three states of a substance are present

99. Critical Temperature
Temperature above which vapor cannot be liquified no matter what pressure is applied

100. Critical Pressure
Minimum pressure required to produce liquefaction of a substance at the critical temperature

101. Critical Point
Ordered pair of
Critical Temperature
& Critical Pressure

103. CO2

104. H2O

108. sulfur