PRAYER

Heavenly Father, we come to you today in prayer,

asking for your wisdom and guidance as we begin
this class. Help us to stay focused and attentive as
we learn and grow together. Give us the strength to
stay motivated while listening to the discussion. We
thank you for the opportunity to grow and learn in
knowledge. May our minds be open to new ideas
and our hearts be filled with understanding. In
Jesus’ name, Amen.
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Polarity of Molecules and
Intermolecular Forces
Group 2
What is Atom?
• The atom is the smallest unit of matter that is composed of three
sub-atomic particles: the proton, the neutron, and the electron.
Protons and neutrons make up the nucleus of the atom, a dense and
positively charged core, whereas the negatively charged electrons
can be found around the nucleus in an electron cloud.

• An atom consists of a positively charged nucleus surrounded by one

or more negatively charged particles called electrons. The number of
protons found in the nucleus equals the number of electrons that
surround it, giving the atom a neutral charge (neutrons have zero
charge).

• When two atoms are close enough to combine chemically and form
chemical bonds with one another, each atom “sees” the outermost
electrons of the other atom. These outer electrons, called valence
electrons, are the most important factors in the chemical behavior of
atoms.
Molecule
A molecule is two or more atoms
connected by chemical bonds, which form
the smallest unit of a substance that retains
the composition and properties of that
substance.
Polar vs Nonpolar
• Polar and non-polar refers to the level in
which two elements equally share a pair of
electrons. Individual bonds can be polar or
nonpolar, as can entire molecules. Polar
means there is unequal sharing of
electrons, while nonpolar means equal
sharing.
 POLAR

NONPOLAR
Molecular Polarity
• When there are no polar bonds in a molecule,
there is no permanent charge difference between
one part of the molecule and another, and the
molecule is nonpolar.
Example: The Cl₂ molecule has no polar bonds
because the electron charge is identical on both
atoms. It is therefore a nonpolar molecule.
Molecular Polarity
• A molecule can possess polar bonds and still be
nonpolar. If the polar bonds are evenly
distributed, the bond dipoles cancel and do not
create a molecular dipole.
• A water molecule is polar because (1) its O-H
bonds are significantly polar, and (2) its bent
geometry makes the distribution of those polar
bonds asymmetrical. The side of the water
molecule containing the more electronegative
oxygen atom is partially negative, and the side of
the molecule containing the less electronegative
hydrogen atoms is partially positive.
Two Kinds of Forces that Operates in a
Molecule
• Intramolecular Forces - Intramolecular forces are the forces that
hold atoms together within a molecule. These forces are very strong
and hold molecules and compounds together.

• Intermolecular Forces – Intermolecular forces are the attractive

and repulsive forces that arise between the molecules of a
substance. These forces mediate the interactions between individual
molecules of a substance. Intermolecular forces are forces that exist
between molecules.
4 Main Types of Intermolecular Forces
1. Ionic Forces – are interactions between charged atoms or
molecules. Positively charged ions are termed cations.
Negatively charged ions are called anions, remember that
“N” in “Anion” stands as “Negative”. The attractive forces
between oppositely charged ions is increased.
2. Hydrogen Bonding – occurs in molecules
containing the highly electronegative elements
Fluorine, Oxygen, or Nitrogen directly bound to
hydrogen. It is an interaction involving a
hydrogen atom located between a pair of other
atoms having a high affinity for electrons.
The dipole of one molecule can align with the
dipole from another molecule, leading to an
attractive interaction that we call Hydrogen
Bonding.
3. Van Der Waals Dipole-Dipole Interactions – other
groups besides hydrogen can be involved in polar
covalent bonding with strongly electronegative atoms.
For instance, each of these molecules contains a
dipole.
These dipoles can interact with each other in an
attractive fashion, which will also increase the boiling
point. However, since the electronegativity difference
between carbon (2.5) and the electronegative atom
such as nitrogen or oxygen is not as large as it is for
hydrogen (2.2), the polar interaction is not as strong.
These forces tend to be weaker than in hydrogen
bonding.
4. Van Der Waals Dispersion Forces (“London
Forces”) – the weakest intermolecular forces of
all are called dispersion forces.
That “something” is dispersion forces. Think
about the electrons in the valence shell. On
average, they’re evenly dispersed. But at any
given instance, there might be a mismatch
between how many electrons are on one side
and how many are on the other, which leads to
an instantaneous difference in charge.
 PROPERTY PHENOMENA/DISCUSSION
Surface Tension – caused by cohesive forces (intermolecular forces) • Experimenting with the jar with wire mesh and water not spiling
between molecules allowing liquid to create a thin fil on its surface. over despite being tipped over completely. This is due to H
This causes liquids to acquire a certain shape when put on a Bonding.
container or dropped on surfaces. The bulk of a liquid has a balance • Paper clips in the water experiment.
of intermolecular forces in all direction. Stronger intermolecular bonds • Certain insects or reptiles being able to walk/glide over water.
equates to stronger surface tension.

Viscosity – is the resistance of a liquid to flow. The more viscous a Compare the flow of honey and water
liquid is the thicker its consistency. Stronger intermolecular forces
leads to higher viscosity. Higher surface area or increasing molecular The liquid with the longest time is the most viscous while the one
size also results to greater viscosity due to greater dispersion forces. with the shortest time is the least viscous. Most viscous liquids has
the stringer intermolecular oforces and the least viscous has the
weakest.
Capillary Action – a liquid is able to rise up on a narrow tube. The veins of a tree that acts as straws that bring nutrients up.
Adhesive forces between the tube and the liquid allow the liquid to
exceed its weight. The narrower the tube, the higher the liquid will
reach.
Evaporation – is the process of turning liquid into gaseous form. Liquids with weak intermolecular attractive forces have low heats of
Weaker intermolecular forces equates to greater volatility. vaporization and are volatile—they evaporate easily. Liquids with
strong intermolecular attractive forces evaporate more slowly,
because a greater amount of energy is needed to overcome the
attractive forces between molecules. The intermolecular forces of
attraction between the liquid molecules are broken or disrupted,
causing the transformation into gas.
QUIZ
 I. MULTIPLE CHOICE
1. Which of the following statements is INCORRECT?

a. Polar covalent bonds can be present in a nonpolar molecule.

b. Polar bond forms when electrons are unequally shared by two
atoms in a compound.
c. Polarity of bond and molecular geometry are the two that affect
the polarity of molecules.
d. Polar covalent bond is present if the electronegativity difference
between atoms is equal or less than 0.4.
2.What do you call the relative ability of a bonded
atom to attract shared electron pairs?

a.Electron affinity
b.Electronegativity
c.Ionization energy
d.Metallic property
3. Which of the following is NOT TRUE about CO₂?

a. Is a polar molecule
b. Polar bond is present
c. Has a linear molecular shape
d. Has an electronegativity difference of 1.0
3. What type of intermolecular force is present in
all substances, regardless of polarity?

a. Ionic bond
b. Hydrogen bond
c. Dipole-dipole forces
d. London dispersion forces
3. Which of the following can exhibit hydrogen
bonding among themselves?

a. H₂Te
b. H₂Se
c. H₂O
d. H₂S
 II. TRUE OR FALSE
Instructions: Write TRUE is the statement is correct, otherwise write
FALSE.

1. S and O are bonded by a polar covalent bond because its

electronegativity difference value is 1.0.
2. Atoms with high electronegativity have a greater tendency to
attract electrons toward itself.
3. Polarity of molecule are determined both by polarity of bonds and
molecular geometry.
4. Among C-Cl, H-Cl, C-H and Cl-Cl, only Cl-Cl is polar.
5. Methyl alcohol, CH₃OH, is a nonpolar molecule.
III. ESSAY
Instructions: Determine whether the bond is polar or nonpolar.
Solve and explain why it is polar or nonpolar in at least 2 to 3
sentences.

1.Cl (3.0) and Br (2.8)

2.O (3.5) and S (2.5)
THANK YOU!