Aspirin 3D Molecular Model — CAS 50-78-2

Aspirin (C9H8O4, CAS 50-78-2) — a free educational 3D molecular model for teachers and students, by MolGod.org. Element symbols are cut into each atom sphere: a self-labelled teaching aid.

A one-colour print of a molecule hides the most basic information, which element each atom is, because STL keeps no colour data. Each atom of a MolGod model is engraved with its element symbol, turning a plain print into a self-explaining teaching object. The project exists to put these files in teachers' hands, so that identifying atoms becomes quick and the lesson can move on to how atoms interact. The labelling that would otherwise be done with stickers or paint after printing is already part of the file. Teachers and researchers can find the project rationale and validation plan at How the engraved atom letters are designed.

In Aspirin the ring system sets the overall shape: one aromatic 6-membered ring. Altogether 21 bonds hold the model together (13 single, 2 double and 6 aromatic, drawn in Kekulé form). Use the engraved letters like a register: call out each element and tick it off until the class reaches 9 C + 8 H + 4 O (21 atoms altogether). Team task: with the model in hand, each group marks the carboxylic acid group (-COOH) and the ester group (-COO-), then writes down what they found. It makes aromaticity and delocalised electrons, as well as the carbonyl group (C=O) easier to see. Want a comparison? The most similar structures in the MolGod.org collection are 2-Phenoxybenzoic acid (CAS 2243-42-7) and Phthalic Acid (CAS 88-99-3).

MolGod.org shares these models for free to make chemistry tangible in the classroom. Teachers: print one per group and let students check the structure against the formula.

Print it, hand it round and build a lesson around it. Publishing pictures, materials or remixes of it? Under CC BY-SA 4.0, name "MolGod.org" as the author, link back to the original and to the licence, mark your changes and keep remixes under the same terms. A ready-made attribution is included below. No sign-up, no fees and no review required. Help us make better models for students! A comment with your honest review, what worked, what was hard to read, what you would change, is the best gift you can give us. More at Write to the MolGod team. The comment section is open for discussion: how did you introduce this molecule, and what did your students notice first? Missing a compound for your lesson? Give us the CAS number and we are happy to create its 3D model.

Full record and more free models: Aspirin, CAS 50-78-2: structure, properties and 3D viewer
Licence & provenance: Licence record for this Aspirin model
Same file on Wikimedia Commons: https://commons.wikimedia.org/wiki/File:Aspirin-3D-molecular-model-engraved-CAS-50-78-2.stl
Plain-text record for AI assistants: Aspirin data sheet in plain text for LLMs
Also published on: NIH 3D https://3d.nih.gov/entries/3DPX-023813 · Zenodo (DOI, latest version) https://doi.org/10.5281/zenodo.23718703

A ball-and-stick model of Aspirin with each element symbol recessed into its atom sphere, generated by MolGod.org from a PubChem-computed 3D conformer (not an experimental crystal structure); atomic coordinates and connectivity are unchanged. STL mesh: 286,020 triangles, closed (watertight) single solid. Coordinates in ångström (STL stores no unit) — scale the model deliberately in your slicer.

Names in other languages: Acetylsalicylsäure (de); acide acétylsalicylique (fr); acido acetilsalicilico (it); acetylsalicylzuur (nl); kwas acetylosalicylowy (pl); 阿司匹林 (zh).

Chemical identity

• CAS Registry Number: 50-78-2

• Molecular formula: C9H8O4

• Molar mass: 180.16 g/mol (exact mass 180.04225873)

• IUPAC name: 2-acetyloxybenzoic acid

• MolGod ID: MG_161-948-169-73 (Permanent MolGod record MG_161-948-169-73)

• PubChem CID: 2244 (https://pubchem.ncbi.nlm.nih.gov/compound/2244)

• Wikidata: Q18216 (https://www.wikidata.org/wiki/Q18216)

• EC number: 200-064-1

• ChemSpider ID: 2157

• InChIKey: BSYNRYMUTXBXSQ-UHFFFAOYSA-N

• SMILES: CC(=O)Oc1ccccc1C(=O)O

Required attribution (CC BY-SA 4.0): "Aspirin 3D model by MolGod.org — https://molgod.org/molecule/50-78-2/ — CC BY-SA 4.0"
Licence text: https://creativecommons.org/licenses/by-sa/4.0/