Intermolecular Forces

Several videos illustrate physical processes or chemical processes. Students use a guided-inquiry activity sheet to classify the starting and ending substances and to identify the processes as physical or chemical.

Heating water from room temperature to boiling water and measuring the temperature of the liquid versus time produces a portion of the Heating Curve for water.

Water Vapor Dynamic Equilibrium Open and Closed Systems evaporation and condensation

London Dispersion Forces Between Three Atoms

Students work in groups to construct 3D molecular models. and connect the models by rubber bands representing an intermolecular force. Students a. identify the partial positive charge atoms and the partial negative charge atoms in each model that are involved in the IMF, b. calculate the difference in electronegativity between the opposite charged atoms, c. select the appropriate rubber band width to correlate with the strength of the IMF between models, d. correlate the strength of the IMF to a physical property of the liquid state of the compound - boiling point, vapor pressure, and Heat of Vaporization.

Activity Parts I and II: Students work in pairs to model intermolecular forces by labeling and manipulating plastic arrows and rectangles: General structures, IMFs in pure substances, IMFs in a mixture. Activity Part III: Students work in pairs by labeling and manipulating plastic arrows and rectangles with specific structures, or real compounds: KBr, ethane, ethanol, dimethy ether; identify IMFs in pure substances and IMFs in a mixture, place the arrow with the IMF to connect opposite charges.

A drop of acetone evaporates faster than ethanol, the ethanol evaporates faster than a drop of water.