(40) GCSE Chemistry Revision "The Three States of Matter"

States of Matter

Overview

• Three common states of matter: solids, liquids, gases.

Solids

• Particle Arrangement:

  • Particles are packed together in a regular pattern.

  • Almost no spaces between particles.

• Properties:

  • Extremely hard to compress.

  • Fixed shape; cannot flow from place to place.

  • Particles can only vibrate but cannot move freely.

Liquids

• Particle Arrangement:

  • Particles are close together but not in a fixed arrangement.

  • Less regular than solids, allowing for movement.

• Properties:

  • Also hard to compress due to close arrangement.

  • Take the shape of their container; can flow from place to place.

  • Particles can move around each other.

Gases

• Particle Arrangement:

  • Particles are widely spaced apart.

• Properties:

  • Extremely easy to compress due to large spaces.

  • Fill the space of their container.

  • Particles move quickly and randomly.

Changes of State

Melting

• Occurs when heating a solid.

• Change from solid to liquid at the melting point.

• Requires energy to overcome forces of attraction between particles.

• More kinetic energy in liquid state than in solid state.

Freezing

• Occurs when cooling a liquid.

• Change from liquid back to solid at the melting point (same as freezing point).

• Forces of attraction reform as particles slow down.

Boiling

• Occurs when heating a liquid.

• Change from liquid to gas at the boiling point.

• Requires energy to break forces of attraction.

• Stronger attractions result in higher boiling points.

Condensing

• Occurs when cooling a gas.

• Change from gas back to liquid at the boiling point.

• Forces of attraction reform as particles slow down.

Factors Affecting Melting and Boiling Points

• Strength of forces of attraction between particles determines energy needed to change states.

• Example:

  • Candle Wax: Lower melting point due to weaker forces of attraction.

  • Sodium Chloride: Higher melting point due to very strong forces of attraction.

Limitations of the Simple Particle Model (Higher-tier)

• Assumptions of the Model:

  • Assumes all particles are solid spheres (not true; they have different shapes).

  • Assumes no forces between particles (incorrect; forces of attraction significantly affect state changes).

• Understanding these limitations is crucial for accurately discussing physical properties.