Intermolecular Forces and

1
Intermolecular Forces and Bonding in Solids
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Different States of Matter
3 States
Solid state - ice
Liquid state - water
Gas state - water vapor
3
Intermolecular Forces
Intermolecular forces are forces between
molecules.
Intramolecular forces hold atoms together in a
molecule.

• Intermolecular vs Intramolecular
• 41 kJ to vaporize 1 mole of water (inter)
• 930 kJ to break all O-H bonds in 1 mole of water
  (intra)

Measure of intermolecular force boiling
point melting point DHvap DHfus DHsub
4
Intermolecular Forces
Dipole-Dipole Forces Attractive and repulsive
forces between polar molecules
solid
5
Intermolecular Forces
Hydrogen Bond a special dipole-dipole
interaction between the hydrogen atom in a polar
N-H, O-H, or F-H bond and an electronegative O,
N, or F atom.
A B are N, O, or F
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Intermolecular Forces
Dispersion Forces Attractive forces that arise
as a result of temporary dipoles induced in atoms
or molecules
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Dispersion Forces among Nonpolar Molecules
instantaneous dipoles
8
Intermolecular Forces
Polarizability is the ease with which the
electron distribution in the atom or molecule can
be distorted.

• Polarizability increases with
• greater number of electrons
• more diffuse electron cloud

9
Intermolecular Forces
What type(s) of intermolecular forces exist
between each of the following molecules?
CH4
CH4 is nonpolar dispersion forces.
SO2
SO2 is a polar molecule dipole-dipole forces.
There are also dispersion forces between SO2
molecules.
HF
HF is a polar molecule dipole-dipole forces.
Hydrogen is bounded to F. Hydrogen bonds exist.
There are also dispersion forces between HBr
molecules.
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Structures and Types of Solids
A crystalline solid possesses rigid and
long-range order. In a crystalline solid, atoms,
molecules or ions occupy specific (predictable)
positions.
An amorphous solid does not possess a
well-defined arrangement and long-range molecular
order.
A unit cell is the basic repeating structural
unit of a crystalline solid.
Unit Cell
Unit cells in 3 dimensions
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Seven Types of Unit Cells
12
Three Types of Cubic Cells
4 atoms/unit cell
1 atom/unit cell
2 atoms/unit cell
(8 x 1/8 1)
(8 x 1/8 1 2)
(8 x 1/8 6 x 1/2 4)
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14
The Striking Beauty of Crystalline Solids
15
Three Types of Crystalline Solids
atomic solid
ionic solid
molecular solid
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Types and Properties of Solids
17
Metallic Crystals

• Lattice points occupied by metal atoms
• Held together by metallic bonds
• Soft to hard, low to high melting point
• Good conductors of heat and electricity

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MO Energy Levels as a Function of the of AO
19
The band of MOs in lithium metal
Conduction Band
Valence Band
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Covalent Crystals

• Lattice points occupied by atoms
• Held together by covalent bonds
• Hard, high melting point
• Poor conductor of heat and electricity

diamond
graphite
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Graphite Consists of Layers of Carbon Atoms
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Electrical Conductivity in Graphite
sp2 hybridization
Delocalized p orbitals
conductor
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Electrical Conductivity in Diamond
sp3 hybridization
localized s orbitals
insulator
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Conductor, Semiconductor, and Insulator
conductor
insulator
semiconductor
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Doped Semiconductors
n-type
p-type
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Chemistry In Action High-Temperature
Superconductors
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Acknowledgment
Some images, animation, and material have been
taken from the following sources Chemistry,
Zumdahl, Steven S. Zumdahl, Susan A. Houghton
Mifflin Co., 6th Ed., 2003 supplements for the
instructor General Chemistry The Essential
Concepts, Chang, Raymon McGraw-Hill Co. Inc.,
4th Ed., 2005 supplements for the
instructor Principles of General Chemistry,
Silberberg, Martin McGraw-Hill Co. Inc., 1st
Ed., 2006 supplements for the instructor