Course: Chemistry
Chapter/lesson:
Chapter 8: Intermolecular Attractions
Lesson Objectives:
• Describe the types of attractions
between molecules.
• Explain how intermolecular
attractions between molecules
influence the bulk properties of a
material.
Lesson Objectives:
5/2/2023
Standards:
HS-PS1-3: Plan and conduct an investigation to gather evidence to
compare the structure of substances at the bulk scale to infer the
strength of electrical forces between particles.
HS-PS1-A-3: The structure and interactions of matter at the bulk
scale are determined by electrical forces within and between atoms.
HS-PS3-5: Develop and use a model of two objects interacting
through electric or magnetic fields to illustrate the forces between
objects and the changes in energy of the objects due to the
interaction.
Bell-Work/ Teacher Demo:
1. Why did the hand sanitizer dry so much faster than the
water?
2. What do you notice about the drops of water and the
isopropyl alcohol on the bench?
1
Forces of Attraction
There are 2 types of forces: INTRAmolecular and INTERmolecular forces of
attraction.
Forces of
Attraction
INTRAmolecular
Ionic Bond
Covalent Bond
INTERmolecular
Metallic Bond
London
Dispersion
Diploe-Dipole
Hydrogen Bond
INTRAmolecular forces (bonds) hold atoms together. INTERmolecular forces hold molecules
together. Which forces are stronger? Intramolecular attractions are stronger than intermolecular bonds.
Lesson Objectives:
5/2/2023
2
Attractions between Molecules
Among other things, these
attractions are responsible
for determining whether a
molecular compound is a
gas, a liquid, or a solid at a
given temperature.
Lesson Objectives:
5/2/2023
3
Attractions between Molecules
Van der Waals Forces
The two weakest attractions
between molecules are
collectively called van der Waals
forces, named after the Dutch
chemist Johannes van der Waals.
Van der Waals forces consist of
dipole interactions and
dispersion forces.
Van der Waals
Forces
Lesson Objectives:
5/2/2023
4
In groups of 3-4
Choose one of the 3 intermolecular bonds
You will need to produce a PowerPoints or
poster
Points to include
• Explain how the bond is formed
• Include images
• Examples
Lesson Objectives:
5/2/2023
5
IM Forces effects on Macroscopic Properties
Bulk properties such as melting point, boiling point and
volatility depend on intermolecular attractions. Strong IM
forces, such as hydrogen bonding and dipole interactions, hold the
molecules together more tightly than weaker dispersion forces.
Volatility is a measure of how easily a liquid
evaporates. Volatile liquids have a greater
number of molecules in the gas phase above
the liquid. The stronger the IM force, the
lower the volatility because the molecules are
held more strongly in the liquid phase,
preventing them from going into the gas
phase.
Lesson Objectives:
5/2/2023
6
IM Forces effects on Macroscopic Properties
Melting Point and Boiling Point:
Molecular substances tend to melt and boil at lower temperatures
than ionic or metallic compounds because IM attractions are weaker
than ionic and metallic bonds.
The stronger the IM forces, the higher the melting and boiling points
because it takes more energy to separate the molecules.
Lesson Objectives:
5/2/2023
7
Like dissolves like
A simple way to predict which
compounds will dissolve in
other compounds. Polar
compounds dissolve polar
compounds, non-polar
compounds dissolve nonpolar compounds, but
polar and non-polar will
not dissolve each other.
Lesson Objectives:
5/2/2023
8
Exit Ticket
• Please complete the
intermolecular forces quiz.
Formative link is on GC.
• Teacher’s link:
https://app.formative.com/assign
/YZK3CX
5/2/2023
Lesson Objectives:
9