2014/08/06
COMPARISON OF THE THREE
PHASES OF MATTER.
DIFFERENT TYPES OF
INTEMOLECULAR FORCES
Do all the exercises in your
studyguide
COMPARISON OF THE THREE
PHASES OF MATTER.
• Matter has three classes
•
THREE STATES OF MATTER.
• Solid
melting
0 0C
liquid
freezing
• ICE
evaporating
100oC
condensation
gas
WATER
STEAM
H 2O
H 2O
H 2O H 2O H 2O
H O H 2O
2
H 2O
H 2O H O
2
H 2O H O
H 2O
2
H 2O
H 2O
H 2O
H 2O
H 2O
INTERMOLECULAR FORCES
The example below shows the different
between/among the intermolecular and
intramolecular forces on the hydrogen iodide
molecule (HI).
INTERMOLECULAR FORCE
ᵟ+
ᵟ+
ᵟᵟ-
H
I ----- H
I
INTRAMOLECULAR FORCES
Matter is anything that occupy space and has
mass.
There are three states of matter:
Solid
Liquid
Gas
INTERMOLECULAR FORCES
The intermolar force is the force of attraction
between the molecules or between formula
units or between formula unit and molecules.
For example:
The force of attraction between/among the water
molecules.
The force of attraction between/among the
sodium chloride formula units.
The force of attraction between/among the
sodium chloride and water molecules.
DIFFERENT TYPES OF THE
INTERMOLECULAR FORCES
There are three main types of intermolecular
forces.
Namely:
Dipole-dipole interaction
Hydrogen bonding
London dispersion force
• These are collectively called Van der Waals
forces.
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2014/08/06
DIPOLE –DIPOLE INTERACTION
This is the force of attraction between the polar
molecules; except NOF.
Examples are:
The force of attraction between HCℓ molecules
DIPOLE –DIPOLE INTERACTION
The name of the above-mentioned intermolecular
force is dipole-dipole interaction.
DIPOLE-DIPOLE INTERACTION
ᵟ+
ᵟᵟ+
ᵟ-
H
Cℓ ----- H
Cℓ
POLAR COVALENT BOND
HYDROGEN BONDING
Hydrogen bonding is a bonding between the
hydrogen atom of one molecule and a highly
electronegative atom of another molecule.
Those highly electronegative atoms must be:
Nitrogen
Oxygen
Fluorine
(NOF)
Hydrogen bonding is a strong dipole-dipole
interaction.
HYDROGEN BONDING
HYDROGEN BONDING
Example of hydrogen bonding is the bonding
between HF molecules.
HYDROGEN BONDING
ᵟ+
ᵟ-
H
ᵟ+
F -------- H
ᵟF
POLAR COVALENT BONDS
HYDROGEN BONDING
• Another example of hydrogen bonding is the
bonding between H2O molecules. See the
figure below.
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2014/08/06
THE EFFECT OF DIPOLE-DIPOLE
INTERACTION ON THE BOILING POINTS OF
HYDROCARBONS
THE EFFECT OF DIPOLE-DIPOLE
INTERACTION ON THE BOILING POINTS OF
HYDROCARBONS
The effect of dipole-dipole interaction on the
boiling points of different hydrocarbon is shown
below.
The boiling point of a substance increase
linearly with the molar mass of that substance.
This relationship is shown below for the boiling
points of different hydrocarbons.
THE EFFECT OF DIPOLE-DIPOLE
INTERACTION AND HYDROGEN BONDING
The above-mentioned relationship does not
hold for the hydrogen containing
compounds that have NOF.
The Figure below shows the comparison
among the boiling points of the hydrogen
containing compounds of group 4A ,
5A,6A and 7A.
THE EFFECT OF DIPOLE-DIPOLE
INTERACTION AND HYDROGEN BONDING
C4H10
C 3H 8
C 2H 6
CH4
THE EFFECT OF DIPOLE-DIPOLE
INTERACTION AND HYDROGEN BONDING
The general trends shows that the boiling
points increase when the molecular
mass increase; except in the molecules
containing NOF.
This shows that there is a strong
intermolecular force between the
molecules containing NOF.
HYDROGEN BONDING
On the figure below; name all the intermolecular
forces:
Do all the exercises in your studyguide
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2014/08/06
INTERMOLECULAR FORCES
INTERMOLECULAR FORCE INVOLVING
NON-POLAR MOLECULES
These are induced intermolecular forces.
The following are examples of the
intermolecular forces involving non-polar
molecules:
Dipole –induced dipole interaction.
London dispersion forces.
DIPOLE -INDUCED DIPOLE
INTERACTION
This is an interaction between the polar and the
non-polar molecules.
In the non-polar molecules, the polarity must be
induced.
The following molecules are examples of some of
non-polar molecules:
N2
H2
Cl2
DIPOLE INDUCED-DIPOLE
INTERACTION
Dipole induced-dipole interaction between HCl
and N2:
DIPOLE INDUCED-DIPOLE INTERACTION
ᵟ+
ᵟ-
H
Cl -------- N
Polar covalent bond
N
DIPOLE INDUCED- DIPOLE
The polarity of the above-mentioned molecules
can be induced by the distortion of their
electron-clouds.
For an example: If the electron-cloud of N-N is
distorted, it becomes polar at that moment.
This can then interact with a polar molecule.
For an example:
N-N can form dipole –induced dipole
interaction with H-Cl, as it is shown below:
LONDON DISPERSION FORCE
This is an interaction between the two non-polar
molecules.
This is called induced dipole-induced dipole
interaction.
It is again called LONDON DISPERSION
FORCE.
In this case, both molecule are non-polar
molecules and the polarity is induced.
Pure covalent bond
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LONDON DISPERSION FORCE
The following molecules are examples of nonpolar molecules:
N2
H2
CH4
London dispersion force can be formed
between the same or different non-polar
molecules.
LONDON DISPERSION FORCE
Example of this is the formation of liquid
nitrogen; as it is shown below:
LONDON DISPERSION FORCE
LONDON DISPERSION FORCE
Example of this is the formation of liquid
nitrogen; as it is shown below:
ION-DIPOLE INTERACTION
This is the force of attraction between an ionic
compound and a polar molecule.
Example is the interaction between the water
molecule and sodium chloride.
In this process, the Na+ and the Cℓ- are
solvated by the water molecules.
N
N -------- N
N
This is called hydration.
PURE COVALENT BOND
ION-DIPOLE INTERACTION
ION-DIPOLE INTERACTION
Another example is the interaction between NaCl
and HCl:
Ion -dipole interaction between two NaCl and HCl
ION-DIPOLE INTERACTION
This is shown schematically on the next slide.
ᵟ+
Na+
Cl- ----------- H
Ionic bond
ᵟCl
Polar covalent bond
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EFFECT ON SOLUBILITY, ETHALPY OF
VAPORIZATION AND FREEZING AND
BOILING
EFFECT ON SOLUBILITY, ETHALPY OF
VAPORIZATION AND FREEZING AND
BOILING.
The figure below shows the relationship between
the solubility of different gases in water at
constant temperature.
EFFECT ON SOLUBILITY, ETHALPY OF
VAPORIZATION AND FREEZING AND
BOILING
EFFECT ON SOLUBILITY, ETHALPY OF
VAPORIZATION AND FREEZING AND
BOILING.
The molar masses of different substances are
compared with their ∆vapHo and the boiling
points of those substances.
The figures below show these relationships.
EFFECT ON SOLUBILITY, ETHALPY OF
VAPORIZATION AND FREEZING AND
BOILING.
EFFECT ON SOLUBILITY, ETHALPY OF
VAPORIZATION AND FREEZING AND
BOILING.
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2014/08/06
EFFECT ON SOLUBILITY, ETHALPY OF
VAPORIZATION AND FREEZING AND
BOILING.
Do all the exercises in your studyguide
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