What is a limitation of simple particle model diagrams?

The correct answer is They do not account for the complexity of real particle interactions..

Comparison lens: State both sides of the comparison so the contrast is explicit rather than implied. This question asks: What is a limitation of simple particle model diagrams. The correct response is They do not account for the complexity of real particle interactions., because the particle model explains the observable property using particles. In Changes of state, the marking point should connect directly to describe limitations of simple particle model diagrams for representing real particles, forces and motion. If the question includes values, the working must keep the appropriate unit and operation; if it is an explanation, it must name the relevant particle behaviour or energy change. This item belongs to Changes of state and the particle model, so avoid answers that switch to a different quantity, confuse heat with temperature, or describe gas pressure without collisions when collisions are the reason. Checkpoint 209 is distinct because it uses this exact question context and the comparison lens rather than a generic particle-model sentence.