Kinetic Theory of Matter
📚 Key Concepts
🔹 Basic Postulates of Kinetic Theory
The kinetic theory explains the behavior of matter based on particle motion.
Main Postulates:
- All matter is made of tiny particles
- Particles are atoms or molecules
- Extremely small and numerous
- Cannot be seen with ordinary microscope
- Particles are in constant motion
- Never completely at rest
- Motion increases with temperature
- Different types of motion in different states
- Particles attract each other
- Forces are always attractive
- Strength varies with distance
- Determine physical properties
- Kinetic energy depends on temperature
- Higher temperature = More kinetic energy
- Kinetic energy opposes attractive forces
- Balance determines state of matter
🔹 Kinetic Energy and Temperature
Average kinetic energy of particles is directly proportional to absolute temperature.
Key Relationships:
- Higher temperature → Higher kinetic energy → More particle motion
- Lower temperature → Lower kinetic energy → Less particle motion
- Absolute zero (-273°C) → Minimum possible kinetic energy
Effects of Temperature Changes:
- Heating: Increases particle motion, weakens attractive forces
- Cooling: Decreases particle motion, strengthens attractive forces
- State changes: Occur when kinetic energy overcomes or succumbs to attractive forces
🔹 Explaining Properties Using Kinetic Theory
1. Expansion on Heating
- Increased kinetic energy pushes particles apart
- Overcome attractive forces partially
- Matter expands in all states
2. Diffusion
- Random particle motion causes mixing
- Faster at higher temperatures
- Occurs in all states but most prominent in gases
3. Pressure in Gases
- Particles collide with container walls
- More collisions = Higher pressure
- Pressure increases with temperature and decreases with volume