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IGCSE Chemistry: States of Matter Summary

Apr 24, 2025

IGCSE Study Buddy: Chemistry Revision

Topic 1: States of Matter

Introduction to Matter

  • Matter: Everything around us with mass and occupies space.
  • Made up of tiny particles.
  • Three states: solids, liquids, gases.

Properties of States of Matter

Solids

  • Fixed volume.
  • Keep own shape.
  • Tightly packed particles.

Liquids

  • Fixed volume.
  • Take shape of container.
  • Particles can move around slightly.

Gases

  • No fixed volume.
  • Take shape of container.
  • Particles move freely.

Particle Arrangement and Motion

Solids

  • Particles very close together.
  • Orderly and regular pattern.
  • Vibrate in place.

Liquids

  • Particles slightly separated.
  • Loosely arranged, disorganized.
  • Slide past each other.

Gases

  • Particles far apart.
  • Highly disordered arrangement.
  • Move rapidly and freely in all directions.

Changes of State

Melting

  • Solid to liquid.
  • Particles gain kinetic energy.
  • Occurs at melting point (e.g., Ice melts at 0°C).

Boiling

  • Liquid to gas.
  • Particles gain more energy.
  • Occurs at boiling point (e.g., Water boils at 100°C).
  • Evaporation: Slow process occurring at various temperatures.

Condensation

  • Gas to liquid.
  • Particles lose kinetic energy.

Freezing

  • Liquid to solid.
  • Particles lose kinetic energy.
  • Occurs at freezing point (e.g., Water freezes at 0°C).

Heating and Cooling Curves

  • Heating Curve: Shows temperature change over time as a substance is heated.
    • Solid warms up, melts, becomes liquid, then boils into gas.
    • Temperature constant during state changes.
  • Cooling Curve: Shows temperature decrease as a substance cools.
    • Reverse process: gas to liquid to solid.

Volume and Gas Behavior

  • Temperature Effect: Increased temperature raises volume as particles move faster.
  • Pressure Effect: Increased pressure decreases volume as particles are compressed.
  • Reduced pressure allows gas expansion.

Diffusion

  • Particles spread from high to low concentration.
  • Continuous motion and collision cause spread until even distribution.

Effect of Molecular Mass on Diffusion

  • Lighter gas particles (e.g., Helium) move faster and diffuse quicker than heavier ones (e.g., Oxygen).

Conclusion

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Note: This summary captures key points from the lecture on states of matter, ideal for revision and study purposes.

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