Kinetic Theory of Matter

States of Matter

Matter exists in three states: solid, liquid, and gas. Each state has unique properties:

Solids

• Have a fixed volume and shape
• Incompressible
• Do not flow

Liquids

• Have a fixed volume but no fixed shape
• Take the shape of their container
• Incompressible
• Flow easily

Gases

• No fixed volume or shape
• Compressible
• Flow in all directions

Kinetic Particle Theory of Matter

• Particles move randomly in straight lines
• Particles are very small with negligible volume
• Intermolecular forces in gases are negligible
• Collisions between particles are elastic (energy is conserved)
• Average kinetic energy of particles is directly proportional to temperature

Applications of Kinetic Theory

Diffusion

Diffusion is the movement and mixing of particles in gases or liquids.

Diffusion in Gases

When bromine is placed in a jar and the cover is removed, it spreads and mixes with air in the jar above due to particle movement.

Diffusion in Liquids

When copper(II) sulfate crystals are added to water, the blue particles spread evenly, forming a uniform solution.

Factors Affecting Rate of Diffusion

• Temperature: Higher temperature increases particle movement, speeding up diffusion.
• Mass of particles: Lighter particles diffuse faster; heavier ones diffuse slower.

Arrangement of Particles

• Solids: Tightly packed in an orderly arrangement; vibrate but don't move freely.
• Liquids: Closely packed but not orderly; can move freely.
• Gases: Widely spaced and randomly arranged; move freely in all directions.

Changes of State

1. Melting: Solid to liquid by heat. Melting point: temperature at which melting occurs.
2. Freezing: Liquid to solid by cooling. Freezing point: temperature at which freezing occurs.
3. Boiling: Liquid to gas by heating. Boiling point: temperature at which boiling occurs.
4. Evaporation: Liquid to gas below boiling point; gives cooling effect as it absorbs heat.
5. Condensation: Gas to liquid; heat is released as particles slow down and come together.
6. Sublimation: Solid to gas without passing through the liquid state; heat is absorbed.