IGCSE Chemistry: States of Matter

Introduction

• States of Matter: Matter is everything with mass and occupies space, composed of tiny particles.
• Three states of matter: Solids, Liquids, and Gases.
• Properties:
  • Solids: Fixed volume, keep shape, tightly packed particles.
  • Liquids: Fixed volume, take shape of container, particles move around.
  • Gases: No fixed volume, fill container, freely moving particles.

Structures of Solids, Liquids, and Gases

• Solids:
  • Particles very close, minimal separation.
  • Tightly packed, orderly arrangement.
  • Particles vibrate in place.
• Liquids:
  • Particles slightly separated, loosely arranged.
  • Can slide past each other, allow flow.
• Gases:
  • Particles far apart, highly disordered.
  • Move rapidly and freely, create pressure.

Changes of State

1. Melting:
   • Solid to liquid when heated.
   • Particles gain kinetic energy, vibrate faster until melting point.
   • Example: Ice (solid) to Water (liquid) at 0°C.
2. Boiling:
   • Liquid to gas when heated further.
   • Particles gain energy, turn into gas at boiling point.
   • Example: Water boils at 100°C.
3. Evaporation vs Boiling:
   • Boiling: Occurs at specific boiling point.
   • Evaporation: Slower, can happen at lower temperatures.
4. Condensing:
   • Gas to liquid when cooled.
   • Particles lose kinetic energy, come closer.
   • Example: Steam condenses to water droplets.
5. Freezing:
   • Liquid to solid when cooled.
   • Particles lose energy, slow down at freezing point.
   • Example: Water freezes at 0°C.

Heating and Cooling Curves

• Heating Curve:
  • Shows temperature change as substance is heated.
  • Solid warms, reaches melting point, becomes liquid.
  • Liquid heats up, reaches boiling point, becomes gas.
  • Temperature constant during state change.
• Cooling Curve:
  • Shows reverse process as substance cools.
  • Gas to liquid to solid.
  • Temperature constant during state change.

Effects of Temperature and Pressure on Gases

• Temperature:
  • Increase in temperature -> gas particles move faster, more kinetic energy -> gas expands.
• Pressure:
  • Increase in pressure -> particles closer together -> decrease in volume.
  • Decrease in pressure -> particles move apart -> increase in volume.

Diffusion

• Process: Particles spread from high to low concentration.
• Kinetic Particle Theory: Particles in constant random motion.
• Effect of Molecular Mass:
  • Lighter gases diffuse faster.
  • Example: Helium (lighter) vs Oxygen (heavier).

Conclusion

• Understanding states of matter and their transitions is crucial for mastering chemistry.
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