Three States of Matter: Solid, Liquid, and Gas

Introduction to Particle Theory

• Particle or kinetic theory explains how particles behave in different states of matter.
• Particles are considered as small solid, inelastic spheres.

Solids

• Structure: Strong forces of attraction hold particles in a fixed, regular lattice structure.
• Properties:
  • Definite shape and volume.
  • Cannot flow like liquids.
  • Particles can vibrate but remain in place.
• Heating Effects:
  • Particles gain energy, vibrate more, and weaken the forces between them.
  • At the melting point, particles break free, and the solid melts into a liquid.

Liquids

• Structure: Particles have weak forces of attraction, allowing free movement and random arrangement.
• Properties:
  • Definite volume but shape can change to fit a container.
  • Can flow.
• Heating Effects:
  • Particles gain energy, move faster, and weaken the forces holding them.
  • At the boiling point, particles break bonds, and the liquid turns into a gas.

Gases

• Structure: Very weak forces of attraction allow particles to move freely.
• Properties:
  • No definite shape or volume; they fill any container.
  • Move with random motion but in straight lines.
• Heating Effects:
  • Particles gain energy and move faster.
  • Gas expands if in an expandable container or increases in pressure if in a fixed container.
• Cooling Effects:
  • Particles lose energy, attractions form, and gas condenses into a liquid.

State Changes and Energy

• Cooling liquids further makes particles lose more energy, forming more bonds, and freezing into solids.
• In a closed system, change of state does not change the mass as particle number is constant.

Density

• Solids: Highest density.
• Liquids: Slightly lower density.
• Gases: Lowest density.

Conclusion: Understanding the behavior and properties of solids, liquids, and gases through particle theory provides insights into how substances change states and interact with energy changes.