Liquids & Solids
Intermolecular
Distance (nm)
Unlike gases, liquids and solids have relatively small
intermolecular distances so that special interactions
are possible.
4
3
2
1
0
Solids
Week 7
Liquids
Gases
CHEM 1310 - Sections L and M
1
Liquids & Solids
16.1
Intermolecular Forces
–
–
–
–
–
–
Ionic Interactions
Dipole-Dipole
Ion-Dipole
Induced Dipole
London Dispersion
Hydrogen Bonding
16.2
The Liquid State
16.3
Structures & Types of Solids
Week 7
CHEM 1310 - Sections L and M
2
1
Types of Non-Bonded Forces
Ionic Interactions
Oppositely
charged ions are
positioned near
each other.
Na+
ClCoulomb’s Law
Week 7
q+ q-
F
d2
CHEM 1310 - Sections L and M
3
Types of Non-Bonded Forces
Dipole-Dipole
Here, oppositely
charged ends are
positioned near
each other.
NET
ATTRACTION
Week 7
CHEM 1310 - Sections L and M
4
2
Types of Non-Bonded Forces
Dipole-Dipole
Here, similarly
charged ends are
positioned near
each other.
NET
REPULSION
Week 7
CHEM 1310 - Sections L and M
5
Types of Non-Bonded Forces
Ion-Dipole
Week 7
CHEM 1310 - Sections L and M
6
3
Types of Non-Bonded Forces
Induced-Dipole
A dipole moment
can be induced
in a nonpolar
atom or molecule
by an ion
Week 7
CHEM 1310 - Sections L and M
7
Types of Non-Bonded Forces
London Dispersion Forces
A temporary
fluctuation of edistribution
induces a temporary
dipole moment.
Dipole moments
align to attract
each other.
Usually made by nonpolar molecules
Week 7
CHEM 1310 - Sections L and M
8
4
Hydrogen Bonds
…N-H
…O-H
…F-H
X
Among the
dipole-dipole
interactions
(which are weak),
H-bonds are strong.
Water Molecules
Week 7
CHEM 1310 - Sections L and M
9
Energy of Bonds
Energy (kJ)
200
150
100
50
2-3
0
Covalent
Bond
Week 7
H Bond
CHEM 1310 - Sections L and M
DipoleDipole
10
5
PRS Question
Which attractive force is likely to predominate
in the association of molecules of F2?
1. Dipole-dipole interactions
2. Ion-Dipole interactions
3. Induced-Dipole interactions
4. Dispersion forces
Week 7
CHEM 1310 - Sections L and M
11
PRS Question
Which attractive force is likely to predominate
in the association of molecules of F2?
ANSWER: #4. Dispersion forces
Dispersive forces involve
non-polar atoms or molecules
(like F2) that can induce a
dipole in each other.
Week 7
CHEM 1310 - Sections L and M
12
6
Characteristics of Liquids & Solids
Water
– Know definition and applications of surface tension
– Know definition of capillary action
– Know definition of viscosity
Vapor Pressure
– Know how to calculate Vapor Pressure for a liquid
Boiling Point
Know definitions and trends
Melting Point
Phase Transitions - know names
Week 7
CHEM 1310 - Sections L and M
13
Water
Water expands when it freezes.
Most substances contract when they freeze.
Density of Ice < Density of Water
Vice
>
Vwater
Water exhibits high surface tension –
the resistance of the surface of a liquid to an
increase in its area
Week 7
CHEM 1310 - Sections L and M
14
7
What is Vapor Pressure?
The pressure of a vapor coexisting with a
confined liquid or solid at any temp.
Week 7
CHEM 1310 - Sections L and M
15
Boiling Point
The boiling point is the temperature at which
the vapor pressure of a liquid equals the
external pressure.
Ionic > Polar > Nonpolar
Higher
bp
Week 7
Lower
bp
CHEM 1310 - Sections L and M
16
8
Boiling Point Trends
Week 7
CHEM 1310 - Sections L and M
17
9