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(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.