CHEM 1AA3 Lecture Notes - Intermolecular Force, Van Der Waals Force, Hydrogen Bond

• School: McMaster University
• Department: Chemistry
• Course: CHEM 1AA3
• Professor: Pippa Lock

Document Summary

Van der waals forces: several different types of intermolecular forces. The bp of no is higher than both because of its additional permanent dipole. The alignment of hf dipoles places an h atom between two f atoms. Because of the very small size of the h atom, the dipoles come close together and produce strong dipole-dipole attractions. Although an h atom is covalently bonded to one f atom, it is also weakly bonded to the f atom of a nearby hf molecule. This occurs through a lone pair of electrons on the f atom. Each h atom acts as a bridge between two f atoms. The bond angle between two f atoms bridged by an h atom is about 180o: the type of intermolecular force just described is called a hydrogen bond. Hydrogen bonding in water: the most common substance in which hydrogen bonding occurs, one water molecule is held to four neighbours in a tetrahedral arrangement by hydrogen bonds.