Why IB Chemistry Structure 2 demands a different answer style for a 7
How a 5-level bonding answer becomes a 7: model, evidence, prediction, explanation. Written against the pre-2025 Chemistry guide and kept for reference.
Gamze Akın3 min read
Note (July 2026): This article was written against the pre-2025 IB Chemistry syllabus. From the May 2025 examination session a new guide is in force: Paper 3 and the option units were removed and the content was reorganised into Structure 1-3 and Reactivity 1-3. The article is kept online for reference. For the current syllabus and exam structure see IB Chemistry tutoring.
Related reading
How to read Structure 1 in IB Chemistry: from the kinetic molecular theory to metallic lattices6 ESS Paper 2 calculation rows that decide a level 5 from a level 6How to read an ESS stimulus when the data contradicts the caption: a Section A triage method
Frequently asked questions
How many marks does IB Chemistry Structure 2 usually carry on Paper 2?
In a typical Paper 2, Structure 2 carries roughly 14 to 22 marks across one short structured question, one comparison question, and a longer integrated question that links bonding to enthalpy or periodicity. The exact distribution shifts by session, but the structural weighting is stable enough that preparation time should be split at least 2:1 in favour of Structure 2 over Structure 1.
What is the fastest way to improve a Structure 2 Paper 2 answer from a 5 to a 7?
The fastest fix is to add the explanation sentence that links the bonding model to a physical property. A 5-level answer usually names the model and gives one piece of evidence; a 7-level answer adds the prediction and the explanation. Practising the four-sentence chain - model, evidence, prediction, explanation - on ten unfamiliar compounds is the most efficient single intervention.
Do I need to memorise the Born-Haber cycle for IB Chemistry Structure 2?
Yes, the Born-Haber cycle is a required instrument in Topic 5 and the mark scheme assumes the candidate can read the cycle as well as draw it. Candidates who cannot reproduce the cycle from memory lose the lattice-energy step in any question that bridges Structure 2 with enthalpy. The cycle should be drawn from blank paper at least once a week during the preparation window.
Is hydrogen bonding a Structure 2 topic in IB Chemistry?
Hydrogen bonding sits inside the Structure 2 cluster in the IB Diploma chemistry guide, classified as one of the intermolecular forces that operates between molecules. It is a common source of lost marks because candidates often describe hydrogen-bonded substances as "covalent" without distinguishing the intermolecular force from the intramolecular bond. The mark scheme reads for the intermolecular-force vocabulary in addition to the bond-type vocabulary.
How does Structure 2 show up in the IB Chemistry Internal Assessment?
Structure 2 is not the primary focus of the Internal Assessment, but the rubric rewards candidates who can rationalise the bonding and structure of the chemicals used in their investigation. A short paragraph that connects the bonding of the reagents to the observation being measured strengthens both the Personal Engagement and the Conclusion criteria, and it gives the IA a second reader-facing demonstration of Structure 2 mastery.