# Source, arithmetic and rights ledger · 29 September 2026

| Source | Precisely what was checked; reuse boundary |
| --- | --- |
| [QCAA Chemistry General landing](https://www.qcaa.qld.edu.au/senior/senior-subjects/syllabuses/sciences/chemistry) and [2025 v1.3 official PDF](https://www.qcaa.qld.edu.au/downloads/senior-qce/syllabuses/snr_chemistry_25_syll.pdf) | Current version for 2026+ completions, Unit 1 title/objectives, Topic 1 *Properties and structure of atoms* 20h, printed pp.19–22 first atomic/isotope/periodic/SHE bullets, 55h unit and Units 1–2 school assessment on pp.5–6. Official PDF text was read live. We link and point to locations, not reproduce QCAA diagrams/pages or claim endorsement. Recheck before adoption. |
| [IUPAC Gold Book: atomic number](https://goldbook.iupac.org/terms/view/A00499), [mass number](https://goldbook.iupac.org/terms/view/M03726), [isotopes](https://goldbook.iupac.org/terms/view/I03331), [ion](https://goldbook.iupac.org/terms/view/I03158) | Independent terminology check: Z is proton number, A counts nuclear protons and neutrons, isotopes have same Z with different A, and ions carry charge. We wrote new explanations and exercises; no Gold Book definition passages copied. Individual Gold Book terms have their own CC BY-SA terms and collection restrictions; SubjectNest's CC BY notice does not relicense IUPAC content. |
| [CIAAW Standard Atomic Weights 2024](https://ciaaw.org/atomic-weights.htm) and [Isotopic Compositions 2024](https://www.ciaaw.org/isotopic-abundances.htm) | Checked symbol/Z pairs and example isotope mass numbers: B-10/11, C-12/13, O-16, F-19, Na-23, Mg-24/26, Cl-35/37 and Ca-40. Also confirmed **decimal atomic weight differs from one isotope's integer mass number**. We do not use any real abundance values as invented case data or reproduce CIAAW tables. |
| [NIST magnesium isotope composition](https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Mg) | Independent spot-check for Mg Z12 and Mg-24/Mg-26 existence. Our paper card's charged state is given for bookkeeping; this table is not evidence of a sample, reaction or free-ion stability. |

**Calculation method:** For each specified paper nuclide, p=Z and n=A−Z. Neutral e=Z. Given monoatomic charge q (integer elementary-charge units), e=Z−q, so `p−e=q`; p+n=A checks the nuclear count. A Python arithmetic audit in `verify_pack.py` recomputes every check-key triple and selected practice triples rather than trusting typeset answers. Values and context names are original presentation choices; none is an actual assay, safety evaluation, medical claim or radiation exercise.

**Originality and licence:** All case files, scripts, tasks, answers and printable diagrams are newly authored SubjectNest content © NeuroForgeIO Pty Ltd 2026, [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). Credit SubjectNest, link the licence, indicate changes. QCAA, IUPAC, CIAAW and NIST retain their own rights; only sourced scientific facts and links, not their tables, images, questions or substantial wording, were used. The generated SVGs request DejaVu Sans; the installed font's complete notice is included in [font rights](print/FONT-RIGHTS.md) and [font licence file](print/dejavu-font-copyright.txt). No external illustration, audio, cultural story, translated worksheet, proprietary simulation, real sample data or copied exam question is included.

**Claim boundaries:** Files are fictional paper species and display labels. A label does not certify a real product's chemistry, health effects, purity, environmental impact or provenance. No classroom pilot, translation check, specialist access review, cultural review, lab result or measured learning impact has occurred.