Exam Focus

Frequency: High — states of matter questions appear in most OCR J248, AQA 8462 and Edexcel 1CH0 papers, typically worth 3–6 marks.

Typical question stems:

• "Describe the arrangement and movement of particles in a [solid/liquid/gas]." (3 marks)
• "Explain why the temperature does not change during melting." (3 marks)
• "Explain why substance A has a higher melting point than substance B." (3 marks)
• "Give two limitations of the simple particle model." (2 marks)
• "Use the kinetic particle model to explain the shape of the heating curve." (4–5 marks)

For full marks on explanation questions: You must use causal language — "because", "therefore", "which means". Simply listing facts without connecting them scores Level 1 only. Examiners are looking for a chain: cause → effect → outcome.

Edexcel 1CH0: Examined in Paper 1 (1CH0/1). Edexcel tests the particle model by asking students to describe arrangement and movement in each state and explain changes of state using energy and intermolecular forces. Limitations of the simple particle model (e.g., particles have volume; forces between particles) are frequently tested as 2-mark questions. In Edexcel-style questions, the command word "Suggest" appears frequently — use your chemistry knowledge to apply to an unfamiliar context.