States of Matter: Solid, Liquid, and Gas

Introduction

• Objective: Understand the three states of matter: solid, liquid, and gas.
• Model Used: Particle Theory (also known as Kinetic Theory).
  • Particles are considered as small solid inelastic spheres.

Solids

• Structure: Particles have strong forces of attraction, forming a regular lattice structure.
• Properties:
  • Fixed position and definite shape, can't flow like liquids.
  • Particles can vibrate around fixed positions.
• Change with Heat:
  • Heating increases particle energy and vibrations.
  • At melting point, particles break free from bonds, transitioning to a liquid.

Liquids

• Structure: Weak forces of attraction, particles move freely and are randomly arranged.
• Properties:
  • Definite volume, shape can change to fit a container.
  • Particles stick together fairly compactly.
• Change with Heat:
  • Heating increases particle energy, weakening bonds.
  • At boiling point, particles break bonds, transitioning to a gas.

Gases

• Structure: Very weak force of attraction, particles move freely.
• Properties:
  • No definite shape or volume, fills container.
  • Particles move in straight lines, can travel in any direction.
  • Random motion is due to deflection by walls and other particles.
• Change with Heat:
  • Heating increases energy and speed of particles.
  • In an expandable container: gas expands.
  • In a fixed container: pressure increases.
• Change with Cooling:
  • Cooling reduces energy, forming bonds, transitioning to a liquid.
  • Further cooling transitions liquid to solid.

Density and Mass in Closed Systems

• Mass: Remains unchanged during state changes as the number of particles is constant.
• Density:
  • Solids have the highest density.
  • Liquids have lower density than solids.
  • Gases have the lowest density.

Conclusion

• Understanding these properties and transitions helps explain how substances behave in different states.
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