Intermolecular Forces

Mrs. Teresita B. Moreno

Physical Science

Effects of Intermolecular

Forces

on Properties of Substances

Objectives

Identify

Identify the
intermolecular
forces present in
each of the given
substances,

Compare

Compare the
strengths of
intermolecular
forces in pairs of
substances,

Predict

Predict which of
among the given
substances will
exhibit higher
boiling, melting, and
freezing points,
viscosity and surface
tension, and
solubilities.

Explain

explain the effects of
intermolecular
forces on the
properties of
substances.

Intermolecular Forces of Attraction
(IMFA)

Ion Dipole

H - Bonding
Dipole –

Dipole forces

Dipole –

induces dipole

London

Dispersion

Forces

​Pre-test

Multiple Choice

H-bonding forms when the substances involved are polar and havemolecules with

• H-atoms attached to O, N, F

• C-atoms attached to O, N, F.

• central atoms with O, N, F as attached atoms.

• unshared pair of electrons in the central atom

Multiple Choice

The properties of matter seen in the macroscopic level by intermolecular forces

• bulk

• covalent

• ionic

• individual

Multiple Choice

Which intermolecular forces depends on the polarizability of molecules?

• ion-dipole

• hydrogen bonds

• dipol-dipole

• London dispersion

Multiple Choice

During ion-dipole interactions, the cation causes the

• repulsion of charges among the molecules

• distortion of the electron distribution in the dipole.

• attraction of the (-) ion to the (+) end of a permanent dipole

• formation of (+) ions that are attracted to the permanent dipole.

Multiple Choice

Ion-dipole interaction results from the

• Attraction between an ion and a polar molecule

• Repulsion between a dipole and another dipole

• Repulsion between a polar with a nonpolar molecule.

• Attraction between a polar with another polar molecule

Multiple Choice

What Intermolecular forces are present in the following species?

CH₄

• H-bonding

• Ion-dipole

• London Dispersion Force

• dipole-dipole

Multiple Select

What Intermolecular forces are present in the following species?

NH₃

• H-bonding

• Ion-dipole

• London Dispersion Force

• dipole-dipole

Multiple Choice

What Intermolecular forces are present in the following species?

PCl₅

• H-bonding

• Ion-dipole

• London Dispersion Force

• dipole-dipole

Show the direction of the dipole moment for each molecule.

Substance

LEDS

Shape

Polarity

Intermolecular
Forces Present

1) CH3OH

2) O3

3) CH3NH2

4) I2

5) HF

Drag and Drop

Show the direction pf the dipole moment for CH₃OH.

Shape:​

Placeholder

​

Placeholder

Polarity: ​

Placeholder

Intermolecular forces: ​

Placeholder

_​

Placeholder

_

Drag these tiles and drop them in the correct blank above

tetrahedral

bent

Polar

H- Bonding

London dispersion

dipole - dipole

Non - Polar

Linear

Drag and Drop

Show the direction pf the dipole moment for CH₃OH.

Shape:​

Placeholder

​

Placeholder

Polarity: ​

Placeholder

Intermolecular forces: ​

Placeholder

_​

Placeholder

___

Drag these tiles and drop them in the correct blank above

tetrahedral

bent

Polar

H- Bonding

London dispersion

dipole - dipole

Non - Polar

Linear

Drag and Drop

Show the direction pf the dipole moment for O₃.

Shape:​ ​

Placeholder

Polarity: ​

Placeholder

Intermolecular forces: ​ ​

Placeholder

​ ​

Placeholder

Drag these tiles and drop them in the correct blank above

bent

Polar

London dispersion

dipole-dipole

Non - Polar

Linear

H- bonding

tetrahedral

https://youtu.be/-QqTwJzi7Wo

Activity 1: Factors affecting the strength of intermolecular forces among molecules

Refer to the pairs of substances to answer the questions that follow.

a. NaCl (sodium chloride) and CH4 (methane)

b. CCl4 (carbon tetrachloride) and CHCl3 (trichloromethane or chloroform)

c. NH3 (ammonia) and CH3F (methyl fluoride)

d. PCL5 (phosphorus pentachloride) and PBr5 (phosphorus pentabromide)

e. C5H12 (pentane) and C5H12 (isopentane)

f. F2 (Fluorine) and Br2 (Bromine)

1. Identify the intermolecular forces present in the substances in each pair.

2. Which of the forces predominates in each substance?

3. Choose which substance will have greater intermolecular forces of attraction.

4. Predict which substance in each pair will have higher boiling and melting points.

Properties of substances affected by

intermolecular forces

Surface tension
Viscosity
Boiling point
Melting point
Solubility

Surface Tension

- liquid molecules are attracted to
each other, nut not to air.

- The surface has a net inward force

- liquid molecules are attracted to
each other, but not to air.

- The surface has a net inward force

Surface Tension

Viscosity

- a measure of a liquid’s resistance to flow

- internal friction to overcome intermolecular forces

- Liquids with high intermolecular forces have high
viscosity

- the greater the viscosity of liquid, the more slowly it
flows

Viscosity

https://youtu.be/2Gdxu4XcsbY

Boiling Point and Melting Point

- boiling point depends on the
equilibrium vapor pressure
exerted by the liquid or solid
above the liquid or the solid

- rate of evaporation = the
rate of condensation (closed
container)

-vapor pressure varies with
temperature

Boiling and Melting Point

https://images.app.goo.gl/J8b7v6uWk2NyFfLq8

16

Energy changes accompanying phase changes

Solubility

The ability of substance solid,
liquid or gas to dissolve in a given
substance.

The amount of any substance
dissolved in a solvent depends on
the types of interaction among
molecules, pressure, and
temperature.

“like dissolves like”

Post - Test

Dropdown

Which pair/pairs of substances will dissolve in each other?



CH₃NH₂ and H₂O

​

Select answer

Dropdown

Which pair/pairs of substances will dissolve in each other?



CH₃-CH₃ and CH₃OH

​

Select answer

Dropdown

Which pair/pairs of substances will dissolve in each other?



SO₂ and CH₄

​

Select answer

Dropdown

Which pair/pairs of substances will dissolve in each other?



MgCl₂ and H₂O



​

Select answer

Dropdown

Which pair/pairs of substances will dissolve in each other?



CH₂ = CH₂ and CH₄



​

Select answer

Labelling

Identify the type of intermolecular forces of attraction in each given chemical structure.

Drag labels to their correct position on the image

H-BONDING

LONDON DDISPERSION

DIPOLE -DIPOLE

ION - DIPOLE

Fill in the Blank

____________ is a mesure of a liquid's resistance to flow.

Multiple Choice

The properties of matter seen in the macroscopic level influenced by intermolecular forces

• bulk

• ionic

• covalent

• individual

Multiple Choice

When adhesion is stronger than cohesion, the liquid is pulled

• upward and results to concave meniscus

• downward and results to convex meniscus

• upward and becomes higher than the surrounding liquid

• downward and becomes higher than the surrounding liquid

Multiple Choice

When intermolecular forces are high, the boiling point is expected to be

• low

• high

• dependent on the kind of atoms

• dependent on the number of atoms

Fill in the Blank

_______________ is the ability of liquid molecules to move against gravity.

​Reference

​Teresita B. Moreno