1. Describe the general types of intermolecular forces.
(S11/12PS-IIIc-d-17)
At the end of the lesson, you should be able to:
2. Explain the effect of intermolecular forces
on the properties of substances. (S11/12PS-IIId-e-19)
Adhesion -the action or process of adhering to a surface
or object.
Cohesion -the sticking together of particles of the same
substance.
In our previous episode we learned about the
polarity of molecules. Specifically, bond polarity
and electronegativity. We have discussed how to
determine the overall polarity of molecules by
predicting its molecular geometry. Lastly, we
gain knowledge on the applications of the
concept of polarity through the mixing of
substances such as oil and water and the
removal of dirt.
Today we'll be talking about a
special force of attraction that is
formed between molecules.
Together let us learn about
intermolecular forces and explore
the exciting world of physical
science.
A force may be defined as a push or
a pull. Whenever there is an
interaction between two objects
or entities, force is definitely
present.
walking gif
pushing a table, gif
stretching a rubber band, gif
lifting a box gif
folding a piece of paper gif
pressing the spray bottle of
alcohol gif
We may not see it, but we feel its
effects. To start our discussion let
us recall the four fundamental
forces of nature that governs
everything that happens in the
universe.
This force is the one that holds
protons and neutrons in the
nucleus of an atom.
Do you know that the destructive
power of this force was seen and
experienced during the World War II
year 1945 on the bombing of
Hiroshima and Nagasaki in Japan?
bombing of Hiroshima and
Nagasaki in Japan gif
It binds electrons to the atomic
nucleus, and it basically deals with
the attractive and repulsive
interaction of electrical charges.
It is responsible for some of the
commonly experienced phenomena
like friction, elasticity, the normal
force, and the force holding
molecules together.
Take note that electricity and
magnetism are closely related.
Together they form an
electromagnetic field.
electromagnetic force gif
It might sound weak, but it is actually
involved in the important processes such
as the radioactive decay or the breaking
down of heavy atomic particles which
eventually forms new elements in stars
and supernova explosions.
It causes objects to be pulled
towards the earth.
Gravity ka ba?
Kasi you're always attractive and
never repulsive.
Gravity is purely an attractive
force. Take note also that gravity
is the reason why we stay on the
ground together with the planets
and moons that stay in their orbit.
gravitational force gif
DIRECTION: READ THE QUESTIONS
CAREFULLY AND CHOOSE THE
LETTTER OF THE CORRECT ANSWER.
1. This force is present in all molecules
whether polar or nonpolar.
A. London dispersion forces
B. Dipole-dipole forces
C. Ion-dipole forces
D. Hydrogen bonding forces.
2. This type of force is the result of the electrostatic
attraction between an ion and a molecule containing
a dipole.
A. London dispersion forces
B. Dipole-dipole forces
C. Ion-dipole forces
D. Hydrogen bonding forces.
3. It is one of the strongest type and a special
type of a dipole-dipole interaction.
A. London dispersion forces
B. Dipole-dipole forces
C. Ion-dipole forces
D. Hydrogen bonding forces.
4. It is a type of force that is attractive force
between the positive end of one polar molecule and
the negative end of another polar molecule.
A. London dispersion forces
B. Dipole-dipole forces
C. Ion-dipole forces
D. Hydrogen bonding forces.
Intermolecular
Forces
As we all know matter is made up
of particles that are in constant
random motion that interact with
each other.
The interaction between particles
and their strength determines
certain properties like boiling
points, the temperature at which a
liquid boils and turns to vapor.
Intermolecular force is the
attractive force or bond between
molecules. Which is responsible for
keeping matter in its solid or in its
liquid phase.
The first two are collectively
known as van der Waals force
named after the Dutch physicist
Johannes Diderikvan der Waals
-weakest type of IMFA.
-Named after the German-
American physicist Fritz London.
This force is present in all
molecules whether polar or
nonpolar.
Electrons in this case are constantly
moving but there are times that
electrons are confined to one end
making it partially negative and the
other end becomes partially positive.
What do you think will happen after
this?
Since there is an equal distribution
of electrons it causes non-polar
molecules to be polar temporarily.
Creating a temporary dipole or an
instantaneous dipole.
Have you tried using a saline
solution or salt and water mixture
to relieve the pain caused by sore
throat or mouth sore?
Well, every time we mix an ionic
compound like salt or sodium
chloride and a polar solvent like
water the third type of IMFA is
involved.
Ion-dipole forces are the result of
the electrostatic attraction
between an ion and a molecule
containing a dipole.
The strength of this force
increases as the charge of the ion
increases.
When sodium chloride dissolves in
water it exists as sodium positive
and chlorine negative.
The partial negative oxygen atom
of water is attracted to sodium.
While the partial positive hydrogen
atom of water is attracted to
chlorine.
It is a special type of a dipole-dipole
interaction. And as the name suggests
this force occurs when hydrogen is
bonded to its best friends fluorine oxygen
or nitrogen. three of the most
electronegative elements.
This interaction makes the partially
positive hydrogen of one molecule
interacts with a partially negative
fluorine oxygen or nitrogen atoms in
another molecule.
Together they make very strong
polar bonds just like the water
molecules. This is the reason why
they have high boiling points and
melting points.
Meaning you need a very high
temperature to break the strong
intermolecular forces between the
molecules.
Type of IMFA Present in Relative Strength
London Dispersion ForcesAll moleculesWeak (Increases with the
size of molecule)
Type of IMFA Present in Relative Strength
London Dispersion ForcesAll moleculesWeak (Increases with the
size of molecule)
Type of IMFA Present in Relative Strength
London Dispersion ForcesAll moleculesWeak (Increases with the
size of molecule)
Dipole-dipole ForcesPolar MoleculesModerate (increases with
increasing polarity)
Type of IMFA Present in Relative Strength
London Dispersion ForcesAll moleculesWeak (Increases with the
size of molecule)
Dipole-dipole ForcesPolar MoleculesModerate (increases with
increasing polarity)
Ion-Dipole Forces Solution of ionic
compounds dissolved in
polar solvent
Strong (increases with
increasing ionic charge)
Type of IMFA Present in Relative Strength
London Dispersion ForcesAll moleculesWeak (Increases with the
size of molecule)
Dipole-dipole ForcesPolar MoleculesModerate (increases with
increasing polarity)
Ion-Dipole Forces Solution of ionic
compounds dissolved in
polar solvent
Strong (increases with
increasing ionic charge)
Hydrogen BondingMolecules with H-F, H-O,
H-N bonds
Strong
The forces of attraction that exist
between molecules that comprise
matter is attributed to its physical
properties.
Like density solubility and the two
that have been mentioned earlier
boiling point and melting point.
basilisk lizards gif
The force that causes molecules
on the surfaces of liquid to be
pushed together and form a layer.
And it is not broken by the large
surface covered by their feet.
water strider gif
I bet you have probably heard a lot
about covid 19 testing recently.
One of the types of tests used is
the rapid antibody test.
The procedure uses extracted
blood sample from a person. A
medical practitioner takes a blood
sample from a patient's finger
using a capillary tube.
Interestingly intermolecular forces
also act on this situation making
the contraction and pulling up of
the blood sample in the tube
possible.
It is the ability of liquid molecules
to flow in narrow tubes or porous
material. Liquids in this case flow
against gravity.
capillary action gif
The attraction between like
molecules or cohesionand the
attraction between unlike
molecules or adhesionbring about
capillary action.
The water molecules in our blood
are all the same. And they exhibit
cohesion.
While the attraction between
water and the sides of the glass
tube is adhesion.
Since adhesion is stronger than
cohesion in this scenario the liquid
is pulled upward.
Guess the substance!
-This liquid is considered a
superfood as it contains water
vitamins minerals and enzymes
that give energy to the body.
Guess the substance!
-It also has medicinal properties.
-When sealed in an airtight
container it is one of the few foods
known to have an eternal shelf life.
Guess the substance!
-It does not spoil.
-and finally I would say along with
the bees flying around it is one of the
most delicious substances on earth.
dripping honey gif
Honey is one common example of a
liquid that is thick and flows
slowly.
Do intermolecular forces of
attraction have something to do
with this? Yes of course.
Viscosityis a measure of a liquid's
resistance to flow or in layman's
term the thickness of a liquid.
The greater the viscosity of the
liquid the more slowly it flows.
Liquids that have high
intermolecular forces are highly
viscous.
Like honey, serum, glue, fuel oil and
lubricating grease.
Like honey, serum, glue, fuel oil and
lubricating grease.
Like honey, serum, glue, fuel oil and
lubricating grease.
Like honey, serum, glue, fuel oil and
lubricating grease.
Like honey, serum, glue, fuel oil and
lubricating grease.
Temperature also affects
viscosity the higher the
temperature the lower the liquids
viscosity. Meaning they will flow
much easier.
Let's Recap!
Can you recall the different
properties of matter influenced by
the strength of the intermolecular
forces?
These are boilingand melting
points, surface tension, capillary
action, and viscosity.
These are important considerations when
materials engineer design different
materials for various uses. Thus, the
properties of the material should match
the product's intended environment.
These are important considerations when
materials engineer design different
materials for various uses. Thus, the
properties of the material should match
the product's intended environment and
should not interfere with its function.
For sports equipment like bike frames
composites are used. It is a combination
of two materials with different
properties that if combined produces a
material with added strength efficiency
and durability.
Nowadays aside from aluminum and
steel, bike manufacturers use carbon
fiber composite materials comprised of
carbon atoms that are linked covalently.
Do you know that carbon fiber is five
times stronger than steel? Yet it is
lightweight these allows easy movement
for the user. It is also durable which is
important since great force is applied
when using it.
Just like any ordinary fabric it is woven
then soak in a special kind of liquid.
Afterwards it is heated and molded into
its desired shape.
In our country bamboo or kawayan is also
being utilized as bicycle frames.
Bambike has gained popularity because
many people are looking for sustainable
and environmentally sound products.
Just like the conventional materials
bamboo is also durable. Resistant to
stress and impacts and can offer a
smooth ride as well. Truly a Tatak Pinoy
that we can all be proud of.
Wow the forces of attraction that exist
between molecules though unseen really
plays an important role in many
unbelievable properties of materials that
we use.
Did you know that your brain cells have
just produced a lot of dopamine?
Dopamine makes us feel good. That is
why it is also commonly called as the
happy hormone.
According to studies you can boost its
level by setting realistic goals and
finding ways to achieve them. Just like
what we are doing right now.
Let's Recap
Today you have learned about the
different intermolecular forces of
attraction or IMFA and how it is
related to the different properties of
matter like boiling point, melting point,
surface tension, capillary action, and
viscosity.
You gained more knowledge on some
applications of the concept of IMFA in
designing and making various
materials that we use.
The attraction between some of the
intermolecular forces might seem to be
weak. Just like as humans don't you
think? But you know what I encourage
all of you to acknowledge your
weaknesses.
There is nothing wrong with that. What is
more important is that we work hard in
overcoming them. Believe me from our
weaknesses we can also find strength
and greatness. Keep the faith and don't
give up. #LABANLANG
Materials:
Water
Paper Clip
Basin
Direction:
Let the Paper clip float in the water.
Question: Why does the paper clip
floats in water?
Question: Why does the paper clip
floats in water?
Why does the water rises?
Direction:Read and analyze the
questions and choose the best
answer.
1. Which of the following properties is not
influenced by the type of intermolecular forces?
A. viscosity
B. molar mass
C. boiling point
D. surface tension
2. Liquids can form a spherical elastic film to minimize
surface area. what intermolecular forces are
responsible for the formation of this film in water?
A. ion dipole forces
B. dipole-dipole forces
C. hydrogen bonding forces
D. londondispersion forces
3. When intermolecular forces are high the
boiling point is expected to be:
A. low
B. high
C. dependent on the kinds of atoms
D. dependent on the number of atoms
4. Looking at the diagram of attraction
between two hydrogen chloride molecules
what type of intermolecular force is present
A. ion-dipole forces
B. dipole-dipole forces
C. hydrogen bonding forces
D. London dispersion forces
5. Which of the following materials is used in
making bicycle frames that are lightweight
and durable?
A. silicones
B. polymers
C. composites
D. aggregates
1. Perform an experiment about capillary action.
2. What are the four Biological Macromolecules?