Cambridge IGCSE Chemistry · Syllabus 0620 · States of Matter
Kinetic particle theory
What is Kinetic particle theory?
The model that all matter is made of very large numbers of extremely small particles that are in constant motion, and that the observable properties of a substance follow from how far apart those particles are, how they are arranged, and how they move. Increasing the temperature of a substance increases the average kinetic energy of its particles, so on average they move faster. The model explains the differences between the solid, liquid and gas states, the changes between those states, gas pressure and diffusion.
This definition is part of the States of Matter chapter in Cambridge IGCSE Chemistry.
Examiner tips on Kinetic particle theory
- This is the exception in Topic 1, so read the statement carefully. Everywhere else in this chapter, Core describes and Supplement explains. Statement 1.2.1 asks every candidate to describe and explain diffusion in terms of kinetic particle theory, so the whole particle mechanism in this lesson — random motion, net movement, the counting argument — is Core material and can be asked on the Core papers. Only the effect of relative molecular mass on the rate of diffusion is Supplement, and that is the separate statement 1.2.2 in Lesson G.