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Particle model and mass conservation

Particle model and mass conservation

Particle model of solid, liquid and gas with arrows showing melting, freezing, evaporation, condensation, sublimation and deposition

A change of state happens when a substance moves between solid, liquid and gas without becoming a new substance. In the particle model, solids have particles close together in a regular arrangement, liquids have close but random particles, and gases have particles far apart and moving freely.

Changes of state Lesson

  1. GCSE
  2. /Physics
  3. /Changes of state

Step-by-step lessons on OCR GCSE Physics Changes of state. Each one builds up to exam-style questions. Paper 2 and Paper 4 include synoptic questions that draw on Topics P1–P4, so revisit earlier topics before final exams rather than treating each paper as self-contained.

Lessons