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.