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LESSON PLAN in Intermolecular Forces. Last updated October 03, 2024.

Summary

In this lesson plan, students will review concepts of intermolecular forces.

Grade Level

High school

AP Chemistry Curriculum Framework

This lesson plan supports the following units, topics and learning objectives:

  • Unit 2: Compound Structure and Properties
    • Topic 2.1: Types of Chemical Bonds
      • 2.1.A: Explain the relationship between the type of bonding and the properties of the elements participating in the bond.
    • Topic 2.2: Intramolecular Force and Potential Energy
      • 2.2.A: Represent the relationship between potential energy and distance between atoms, based on factors that influence the interaction strength.
    • Topic 2.3: Structure of Ionic Solids
      • 2.3.A: Represent an ionic solid with a particulate model that is consistent with Coulomb's Law and the properties of the constituent ions.
  • Unit 3: Properties of Substances and Mixtures
    • Topic 3.1: Intermolecular and Interparticle Forces
      • 3.1.A: Explain the relationship between the chemical structures of molecules and the relative strength of their intermolecular forces when: a. The molecules are of the same chemical species. b. The molecules are of two different chemical species.

Objectives

By the end of this lesson, students should be able to

  • list the five types of intermolecular forces.
  • explain London dispersion forces.
  • explain dipole-induced dipoles.
  • explain dipole forces, hydrogen bonding, and ionic bonding.
  • distinguish between all of the above types of intermolecular forces.

Chemistry Topics

This lesson supports students’ understanding of

  • Intermolecular forces
  • Hydrogen bonding

Time

Teacher Preparation: 5 minutes

Lesson: 45 minutes

Safety

  • There are no special safety considerations for this activity.

Teacher Notes

  • This lesson is intended as a review of intermolecular forces.
  • Go through the PowerPoint presentation and have students fill in the correct answers on their student sheets.
  • You may also have students research the answers on their own, and then check their answers with the PowerPoint presentation.

For the Student

Lesson

  1. Intermolecular forces are interactions _________ two or more molecules or atoms.
  • MF is based upon polarity and Coulomb's Law
  • The 5 intermolecular forces, in order of increasing strength (weakest to strongest) are:
  • The stronger the IMF, the greater the interaction between two particles, resulting in a higher melting point and boiling point since it would require more energy (in the form of heat or compression) to disrupt the intermolecular forces present between them and permit a phase change.
  1. London dispersion forces
  • London dispersion forces are present between ALL substances (polar/ non-polar).
  • The only IMF that _____________ particles exhibit are LDF
  • As two particles get closer together, LDF interactions _________ in strength
  • This is because as you decrease the distance of separation (r) between two particles, Coulombic repulsion of the two particles' electron cloud will force electron density to redistribute, inducing a temporary (or instantaneous) dipole in order to maximize attraction and minimize repulsion.
  • As you increase in molecular size (MW), the strength of LDF _____________
  • This is because as you increase in molecular weight, the molecule becomes larger. The larger the molecule, the larger the electron cloud, and therefore the greater the dispersion forces.
  1. Dipole-induced dipole
  • Recall that non-polar substances do _____have a dipole moment
  • When a polar particle approaches a non-polar particle, the polar substance _________a temporary dipole on the non-polar particle that wasn't there originally
  • This temporary dipole occurs in order to __________ Coulombic attraction and__________ Coulombic repulsion
  1. Dipole forces
  • Recall that polar substances ______ dipole moments
  • Dipole forces are present between ____ polar substances
  • The __________ dipole on a polar molecule is Coulombically attracted to a positive dipole on another polar molecule
  • The __________ dipole on a polar molecule is Coulombically attracted to a negative dipole on another polar molecule
  1. Hydrogen bonding
  • Hydrogen bonding is present when a polar substance has a H that is bonded to a highly______________ atom (i.e. N, O, or F)
  • H-bonding is extremely strong; so strong that it can stably maintain the structure of large macromolecules, such as proteins and nucleic acids
  1. Ionic bonding
  • Recall, ions are _______ because they have a permanent dipole
  • Ionic bonds occur between a ______ and a __________ due to the TRANSFER of electrons, resulting in an ionic compound between two ions
  • Ionic bonding is present when there are metal and non-metal ions in solution
  • Ionic bonding is the _________ IMF, and nearly as strong as covalent bonding (the only intramolecular bond)