General Chemistry Lesson

1. KINETIC MOLECULAR
MODELS OF LIQUIDS
AND SOLIDS
CAROLLE P. USITA

2. Content:
• Intermolecular forces of
attraction
• Properties of liquids
• Physical and chemical
properties of water
• Types and properties of solids
• Phase changes
• Phase diagram
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3. INTERMOLECULAR FORCES OF
ATTRACTION
The intermolecular forces of attraction pertain to
forces that hold individual particles such as atoms,
molecules, or ions together. The strength of the
intermolecular forces of attraction is dependent on the
arrangement of the particles, the proximity of particles
relative to one another, and the nature of the interacting
particles. The intermolecular forces of attraction
influence the resulting properties of solids, liquids, and
gases. In solids, for example, the intermolecular forces
of attraction directly affect its melting point and heat of
fusion. 3

4. The intramolecular forces of attraction, on the other
hand, are those responsible for interactions within a
molecule, such as covalent and ionic bonds. One
example would be the different amino acids present in
a certain protein. The functional groups in each amino
acid interact with one another, enabling the protein to
have a folded structure. Generally, intramolecular
forces of attraction are stronger than
intermolecular attractions.
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Intramolecular forces of attraction

5. Intermolecular forces explain the physical
properties of substances. Similar to magnets, the
stronger the intermolecular forces of attraction,
the more difficult it is to pull molecules away from
each other.
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7. TYPES OF IMF

8. 1. London dispersion force
Named after the German-born physicist Fritz
London, this is the weakest among the
intermolecular forces. This dispersion force is
caused by polarization, or the distortion of the
electron cloud brought about by the presence of
a highly charged particle. In this case, the
electron cloud of one atom is attracted to the
positively charged nucleus of another atom.
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9. 9

10. London dispersion is the temporary
attraction between dipoles, which occur
among all types of molecules. It also
determines the physical properties of
nonpolar substances.
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11. The number of electrons in an atom affects the
polarizability of the atom. This is due to the number of
electrons affecting the size of the electron cloud. As a
result, the larger the electron cloud, the higher the
chances of the atom getting attracted by a
positively charged particle. This results in the
formation of temporary dipoles, wherein one end of the
atom is partially positive and the other end is partially
negative. To summarize, the London dispersion
force happens when one molecule with a
temporary dipole exerts a weak attractive force on
another molecule.
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12. 2. Dipole-dipole Interaction
This is an intermolecular force of attraction that
occurs between partially positive and partially
negative ends. This interaction is observed in polar
covalent molecules such as amino acids, wherein the
electrons are shared both by oxygen and carbon
atoms. However, due to the electronegativity of the
oxygen atom, the oxygen atom assumes a partially
negative charge, whereas the carbon atom assumes a
partially positive charge.
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14. The dipole-dipole interaction occurs due
to the attraction between the opposite,
partially charged molecules. The more
polar the molecules are, the stronger the
dipole dipole interaction.
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15. 3. Ion-dipole interaction
This arises from the interaction between an ion
and a polar molecule. If the molecule is an anion
(negatively charged ion), it will be attracted to the
partially positive end of the polar molecule;
however, if the molecule is a cation (positively
charged ion), it will be attracted to the partially
negative end of the polar molecule.
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16. 16

17. 4. Hydrogen bond
A hydrogen bond is a special kind of dipole-dipole
interaction, which is formed when hydrogen bonds
with fluorine, oxygen, or nitrogen. In a hydrogen
bond, the partially positive end of the hydrogen atom is
attracted to the partially negative end of fluorine,
oxygen, or nitrogen. Generally, hydrogen bonds are still
weaker than ionic or covalent bonds, but they are the
strongest intermolecular force of attraction (when
the hydrogen bond is present between two atoms of
two different molecules).
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19. 19

20. Substance
Evaluate its composition
and structure
Is it
polar?
Are ions
present?
Is hydrogen bonding
involved?
Hydrogen
bonding
Is both ionic
and polar?
Covalent
bonding
Dipole-dipole
forces
Ionic bonding
London
dispersion force
NO NO
YES
YES
NO
YES
YES
NO

21. PROPERTIES OF
LIQUID
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22. 1. Viscosity
This property refers to the measure of a liquid's
resistance to flow. The viscosity of a liquid is strongly
dependent on the strength of the intermolecular forces
in play. Highly viscous liquids are those exhibiting
the strongest intermolecular forces. For example,
glycerol, a highly viscous
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23. The actual viscosities of liquids may vary,
but they generally increase when stronger
intermolecular forces are present.
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24. 2. Surface Tension
This refers to the
amount of resistance
needed to increase the
surface area of liquids.
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25. 25

26. The higher the surface tension is, the
stronger the intermolecular force. This
can be observed in hydrogen bonding in
water.
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27. 3. Vapor Pressure
Vaporization is the transformation of a substance
from a liquid to a gas. Vaporization is an endothermic
process as it requires absorption of energy to break
the intermolecular forces of attraction in a liquid.
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28. The large heat of vaporization of water
helps in regulating the temperature of
Earth's surface from the energy of the
sun.
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29. 4. Boiling Point
A liquid boils when its vapor pressure is equal to
the prevailing atmospheric pressure. The normal
boiling point of any liquid is directly influenced by the
existing intermolecular forces of attraction. So if a
stronger intermolecular force of attraction is in
place, the liquid will have a relatively higher boiling
point.
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30. 30

32. PHYSICAL AND
CHEMICAL
PROPERTIES OF
WATER
32

33. Water is the chemical substance with chemical
formula H2O, one molecule of water has two
hydrogen atoms covalently bonded to a single
oxygen atom.
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36. PHASE CHANGES
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37. Freezing
A phase transition where a
liquid turns into a solid when
its temperature is lowered
below its freezing point.
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38. Melting
defined as the point at which
materials changes from a
solid to a liquid. The
temperature at which solid
changes its state to liquid at
atmospheric pressure is
called the melting point of
that liquid. This is the point at
which both liquid and solid
phase exists at equilibrium.
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39. Vaporization
conversion of a substance from
the liquid or solid phase into the
gaseous (vapour) phase. If
conditions allow the formation of
vapour bubbles within a liquid, the
vaporization process is called
boiling. Direct conversion from
solid to vapour is called
sublimation.
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40. Condensation
change of water from its gaseous form (water
vapor) into liquid water.
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41. Sublimation
The process in which solids
directly change to gases is
known as sublimation. This
occurs when solids absorb
enough energy to completely
overcome the forces of attraction
between them. Dry ice is an
example of solids that undergo
sublimation.
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42. PHASE DIAGRAM
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43. https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_General_Chemistry_(Petrucci_et_al.)/12%3A
_Intermolecular_Forces%3A_Liquids_And_Solids/12.4%3A_Phase_Diagrams

44. TYPES AND
PROPERTIES OF
SOLID
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48. Thank you!
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