Molecular modelCopy

Learning Objectives

• Describe qualitatively the molecular structure of solids, liquids and gases in terms of the arrangement, separation and motion of the molecules
• Relate the properties of solids, liquids and gases to the forces and distances between molecules and to the motion of the molecules
• Interpret the temperature of a gas in terms of the motion of its molecules
• Describe qualitatively the pressure of a gas in terms of the motion of its molecules
• Explain pressure in terms of the change of momentum of the particles striking the walls creating a force 
• Show an understanding of the random motion of particles in a suspension as evidence for the kinetic molecular model of matter
• Show an appreciation that massive particles may be moved by light, fast-moving molecules
• Describe this motion (sometimes known as Brownian motion) in terms of random molecular bombardment

Contents to learn

Molecular model
The kinetic molecular model uses this idea that all materials are made up of atoms that behave rather like tiny balls.

Kinetic Theory Of Solids:
In solids the molecules are attached just as if springs representing the electric forces between molecules,hold the molecules together (as shown in figure)this enables the solid to keep a definite shape and volume.
Kinetic Theory Of Liquids:
A model to represent the liquid state can be made by covering about a third of the fitted tray with marbles that represents the molecules (as shown in figure)it is shaken to and from and the motion of the marbles observed.They are able to move around but most stay in the lower half of the tray,so the liquid has a fairly definite volume.

Kinetic Theory Of Gases:

The kinetic theory of gases is briefly given in the table below