This entry presents Sulfurous Acid (H2O3S; CAS 7782-99-2; PubChem CID 1100) as a 3D-printable ball-and-stick model in which every atom carries its engraved element symbol (H, O, S), so the model can be read without a colour key. Atomic coordinates come from the PubChem-computed 3D conformer (not an experimental crystal structure); coordinates and connectivity are unchanged.

Project scope and purpose

MolGod is an open educational-science project that publishes engraved ball-and-stick models of individual chemical compounds. Models are generated deterministically from public structure data and released under CC BY-SA 4.0 together with their identifiers and provenance.

Standard molecular STL files encode geometry only; atom identity, conventionally conveyed by colour, is lost in single-material additive manufacturing. In these models the element symbol is a recessed engraving on each atomic sphere, so atom identity is part of the mesh and remains readable in any print material, visually and by touch.

The design objective is to shorten the time learners need to identify the atoms of a molecule, so that instruction can concentrate on connectivity, bond order and three-dimensional geometry, and to reduce teacher preparation to scaling and slicing a ready file. This is a design rationale: the effect on learning outcomes has not yet been formally evaluated.

Project rationale, related peer-reviewed research and the validation plan: How MolGod engraved molecular models are made.

Structure at a glance

• 6 atoms: 2 H, 3 O, 1 S

• 5 bonds: 4 single, 1 double

• No rings (open-chain structure)

Use in teaching

• Counting task: students tally the engraved symbols (2 H, 3 O, 1 S; 6 atoms) and rebuild the formula H2O3S from the model alone.

File and printing

STL mesh of 89,316 triangles, a closed (watertight) single solid. Coordinates are in ångström and STL stores no unit, so scale the model deliberately in your slicer. Measured bounding box: 3.39 × 3.389 × 2.702 Å; at scale factor 10 (1 Å to 10 mm, file read in millimetres) the print measures about 33.9 × 33.9 × 27.0 mm. SHA-256: f7d7924cb7424005fd2694861b936436ffe0ac53545381bb76d4fdf9fa337d96.

Validation

• InChIKey identical to the PubChem record (PubChem FTP SDF, file dated 2026-10-08): LSNNMFCWUKXFEE-UHFFFAOYSA-N

• Molecular formula identical to PubChem

• Mesh: triangle count in the header equals the actual count; 0 edges not shared by exactly two triangles; 1 connected solid; SHA-256 equal to the published file

Source, licence and identifiers

Full record: Sulfurous Acid 3D molecular model and data (CAS 7782-99-2) · Licence and provenance record: License and provenance of the Sulfurous Acid 3D model · Same file on Wikimedia Commons: File:Sulfurous Acid-3D-molecular-model-engraved-CAS-7782-99-2.stl

• MolGod ID: MolGod ID MG_541-264-353-37

• Wikidata: Q206778

• EC number: 231-973-1

• ChemSpider ID: 1069

• IUPAC name: sulfurous acid

• InChIKey: LSNNMFCWUKXFEE-UHFFFAOYSA-N

• SMILES: OS(=O)O

• Molar mass 82.08 g/mol (exact mass 81.97246510)

Licence: CC BY-SA 4.0 (licence text). Required attribution: "Sulfurous Acid 3D model by MolGod.org — https://molgod.org/molecule/7782-99-2/ — CC BY-SA 4.0".