a summary of chapter 11 the intermolecular forces Chemistry

1. Chapter 11
SUMMARY
Ali Barakat
ali

2. Word Definition
By: Ali Barakat
CHAPTER 11
Phase
A homogeneous part of the system in contact with other parts
of the system but separated from them by a well-defined
boundary.
Dipole-dipole
interaction
Attractive forces between polar molecules
(molecules that poses dipole moment).
H-bonding
A strong type of dipole-dipole interaction, formed between
hydrogen atom in a polar molecule and a high-electronegative
atom in another polar molecule (N, O, F).
INTRAMOLECULAR
FORCES
Attractive forces that holds the atoms together within a
molecule.
INTERMOLECULAR
FORCES
Attractive forces between molecules.
Surface tension The amount of energy required to stretch or increase the
surface of a liquid by a unit area.(J/m2)
Viscosity A measure of a fluid’s resistance to flow.
Cohesion The intermolecular attraction between like molecules.
Adhesion The intermolecular attraction between unlike molecules.
Unit cell The basic repeating structural unit of a crystalline solid.

3. Molar heat of
vaporization
The energy required to vaporize 1 mole of a liquid at its boiling
point.
Molar heat of
fusion
The energy required to melt 1 mole of a solid substance at its
freezing point.
Critical
temperature
The temperature above which the gas cannot be made to
liquefy, no matter how great the applied pressure
Critical pressure the minimum pressure that must be applied to bring about
liquefaction at the critical temperature
Surfactant A substance added to liquid which decreases its surface tension.
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4. By: Ali Barakat
Highlights
INTRAMOLECULAR
FORCES
Attractive forces
that holds the
atoms together
within a molecule.
Stabilize individual
molecules.
Stronger.
INTERMOLECULAR
FORCES
Attractive forces
between molecules.
Responsible for the
bulk properties of
the matter.
 Boiling point.
 Freezing point.
 DHvap
 DHfus
 DHsub
Weaker.
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6. Nucleus &
Inner shell e -
CROSS SECTION OF METALLIC CRYSTALLE
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8. By: Ali Barakat
T2 > T1
At the higher temperature the curve
flattens out.
The higher the temperature, the
greater the number of molecules
with high kinetic energy.

9. 1. The strength of ion-dipole force depends on:
Charge and size of the ion.
Size and magnitude of the dipole moment of the polar molecule.
2. Charges of cations are usually more concentrated than anions that have
the same magnitude.
Because cations are usually smaller than anions.
3. Mg2+ interacts more strongly with H2O molecules than Na2+.
Because Mg2+ has a higher charge than Na+.
Because Mg2+ has a smaller ionic radius than Na+.
Heat of hydration of Mg2+ is greater than heat of hydration of Na+.
4. If we placed an ion or a polar molecule near an atom or a nonpolar
molecule, the electron distribution of the atom (or the molecule) will
be distorted by the force exerted by the ion or the polar molecule
resulting in a kind of dipole called induced dipole
Because the separation of positive and negative ions in the atom or
the nonpolar molecule is due to the proximity of an ion or a polar
molecule.
5. Polarizability
The ease with which the electron distribution in the atom or molecule can
be distorted.
6. As electrons are in continuous motion, a nonpolar molecule could have
an instantaneous dipole.
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10. 7. The likelihood of a dipole moment being induced depends on:-
Charge of the ion OR the strength of the dipole.
The polarizability of the atom or the nonpolar molecule.
8. Polarizability increases with:-
Greater number of electrons.
More diffuse electron cloud.
9. Dispersion force ∝ polarizability ∝ Molar mass (GR???)
 Molecules with larger molar mass tend to have more electrons and
dispersion forces increase in strength by increasing number of
electrons.
 Larger molar mass means a bigger atom whose electron distribution
is more easily distributed because the outer electrons are less
tightly held to the nuclei.
Dispersion force ∝ Low Temperature
Dispersion force ∝ reduced atomic speed
10. Melting point increases while Molar Mass is increasing.
11. At any moment, the atom could have a dipole moment created by the
specific positions of its electron, and it is called instantaneous dipole
because it lasts for just a tiny fraction of second.
12. Instantaneous dipoles cancel each other.
13. Dispersion force: attractive forces that arise as a result of temporary
dipoles induced in atoms and nonpolar molecules.
14. Surface tension ∝ I.M.F
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11. 15. Polarizability enables gases containing atoms or nonpolar molecules to
condense.
16. Cohesion > Adhesion (Mercury)……. Convex meniscus
17. Adhesion > Cohesion (Water)……….. Concave meniscus
18. Surfactant - substance added to liquid which decreases the surface
tension.
19. Viscosity ∝ low temperature ∝ M.M ∝ density ∝ I.M.F
20. Viscosity Units: J/m2 --------- N.s/m2……………….. Kg/(m.s)
21. Surface tension results from the net inward force experienced by the
molecules on the surface of a liquid.
22. Water has maximum density at 40C.
23. In f.c.c
√ ……. √ ..….
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√
.…. ….. √
√
24. In b.c.c
√
√
√
√

12. 25. In s.c.c
26. The equilibrium vapor pressure is the vapor pressure measured when a
dynamic equilibrium exists between condensation and evaporation.
27. A state of dynamic equilibrium, in which the rate of a forward process is
exactly balanced by the rate of reverse process.
28. Molar heat of vaporization (DHvap): is the energy required to vaporize 1
mole of a liquid at its boiling point.
29. Clausius-Clapeyron Equation
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(
).
30. Boiling point: the temperature at which the (equilibrium) vapor
pressure of a liquid is equal to the external pressure.
31. Normal boiling point: the temperature at which a liquid boils
when the external pressure is 1 atm.
32. Critical temperature (Tc): the maximum temperature at which
the gas can be made to liquefy, with no effect for raising the
pressure at any temperature above the critical temperature.

13. 33. The critical pressure (Pc): the minimum pressure that must be
applied to bring about liquefaction at the critical temperature.
34. The melting point of a solid or the freezing point of a liquid is
the temperature at which the solid and liquid phases coexist in
equilibrium.
35. Molar heat of fusion (DHfus): the energy required to melt 1 mole
of a solid substance at its freezing point.
36. Molar heat of sublimation (DHsub): the energy required to
sublime 1 mole of a solid.
37. Due to Hess’s Law: DHsub = DHfus + DHvap
38. A phase diagram summarizes the conditions at which a
substance exists as a solid, liquid, or gas.
39. An increase in the pressure causes the boiling point to increase
and melting point to decrease.
Because, ∝
And so an increase in the pressure of ice favors the liquid phase.
40.
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