States of matter, changes of state, and the kinetic particle theory

The particulate nature of matter — solids, liquids, gases, and the kinetic theory that explains changes of state — is well established at GCSE and transfers cleanly to IB. The IB extends it with the ideal gas law (PV = nRT) and the Maxwell–Boltzmann distribution, but the foundation is identical. A student who can describe states of matter in terms of particle arrangement and motion, and explain changes of state as energy breaking intermolecular forces (not covalent bonds), arrives ready.