K-01: Writing and balancing chemical equations, and state symbols

IB sub-topics affected

EditorialSub-topic tagging is this site’s own editorial judgement, not the IB’s.

R2.1 How much? The amount of chemical change
R2.3 How far? The extent of chemical changeHL
R3.2 Electron transfer reactionsHL

Load-bearing everywhere: Reactivity 2.1 (stoichiometry), 2.3 (equilibrium expressions from the balanced equation), 3.2 (half-equations). IB adds ionic and half equations but the underlying skill — conserving atoms and charge — transfers 100%.