Module 2 Intro

1. Module 2 Intro

1.23. Page 5

Lesson 4

Module 2—Chemical Compounds

Read

Can you think of a reason why the boiling points of some compounds cannot be explained using the hypothesis for London and dipole-dipole forces? Maybe another type of intermolecular bonding force exists.

Read “Hydrogen Bonding” on pages 111 and 112 in your textbook.

A diagram showing four water molecules, each represented as two white spheres joined to a single red sphere. Black double-sided arrows appear between the red and white spheres of adjacent molecules.

Watch and Listen

View the animation of the hydrogen bonding in ammonia.

Use a diagram of your choice to explain why hydrogen atoms become attracted to neighbouring nitrogen atoms in ammonia. Send a copy of your diagram to your teacher.

The boiling points of water, ammonia, and hydrogen fluoride demonstrate that the hydrogen bonding is stronger than other dipole-dipole forces.

Self-Check

SC 5. Complete the following table. The first row has been done for you.

Molecule	Structural Formula	Shape	Polarity	Types of Intermolecular Forces
HBr	H–Br	linear	polar	dipole-dipole
HF
AsH3
BF3
HI

Check your work.

Self-Check Answer

SC 5.

Molecule	Structural Formula	Shape	Polarity	Types of Intermolecular Forces
HBr	H–Br	linear	polar	dipole-dipole
HF	H–F	linear	polar	hydrogen bonding
AsH3	H – As – H \| H	trigonal pyramidal	polar	dipole-dipole
BF3	F – B – F \| F	trigonal planar	nonpolar	London
HI	H–I	linear	polar	dipole-dipole

Read

Read “Physical Properties of Liquids” on page 113 of your textbook.