JSS 2: PARTICULATE NATURE OF MATTER

The particulate nature of matter means that all matter is made up of tiny particles (atoms or molecules) which are too small to be seen with the naked eye.

These particles are constantly moving and have spaces between them.

Assumptions of the Kinetic Theory of Matter

1. All matter is made up of tiny particles.

2. The particles are in constant motion.

3. There are spaces between the particles.

4. The particles attract one another with forces of attraction.

5. The higher the temperature, the faster the particles move.

States of Matter and Their Particle Arrangement

The states of matter are:

1. Solid state

2. Liquid State

3. Gaseous state

                            Solid State

    Properties of Solid State of matter:

1. They have definite shape and volume

2. They have strong intermolecular forces

3. Their particles are closely packed and orderli

4. Their particles are Incompressible

5. They have high density

6. Particles vibrate about fixed positions

Examples: Ice, iron, wood

                          Liquid State

      Properties of Liquid State of matter

1. They have no definite shape (they take the shape of their container)

2. They have definite volume

3. They have weaker intermolecular forces than solids

4. Their particles are close but can move past one another

5. They are slightly compressible

6. They have moderate density (less than solids but greater than gases/

Examples: Water, oil

                     Gaseous State

Properties of gaseous state of matter 

1. They have no definite shape (they take the shape of their container)

2. They have no definite volume (they expand to fill the container)

3. Their particles have very weak intermolecular forces

4. Their particles are far apart and move freely in all directions

5. They are highly compressible

6. They have a very low density

7. Particles move at high speed

8. Gases can flow easily (they are fluids)

9. They diffuse very rapidly

10. Exert pressure on the walls of their container

Examples: Air, oxygen, perfume vapour

Evidence of the Particulate Nature of Matter

1. Diffusion

2. Dissolution

3. Brownian Motion

4. Compression of Gas

                            Diffusion

The movement of particles from a region of high concentration to a region of low concentration.

Example: Smell of perfume spreading in a room.

                         Dissolution

When sugar or salt dissolves in water, the particles of the solid mix with the particles of water.

                     Brownian Motion

The random movement of tiny particles that are suspended in a fluid. They can be seen under a microscope.

                  Compression of Gas

Air can be compressed, showing that there are spaces between particles.