Where does the chemical data come from?
All chemical data, structures, identifiers, and images are fetched live from the official PubChem PUG REST API maintained by the U.S. National Institutes of Health (NCBI).
What are the different description sources?
You can choose between three sources:
• PubChem – Official description
• Wikipedia – Clean first-paragraph summary
• AI (Gemini) – Short, readable description with real-world uses (requires free API key)
How do I set my preferred description source?
Click the ⚙️ gear icon next to the “Description” title. Your choice is saved in your browser and will be used automatically for every new search.
Why is the 3D model sometimes missing?
Not every compound in PubChem has a computed 3D structure. When unavailable, the app automatically falls back to the 2D image and shows a small notice.
What do InChI and InChI Key mean?
InChI is a unique text representation of a molecule’s structure. InChI Key is a shortened, searchable version of it (27 characters). Click the ℹ️ icon next to them for a simple explanation.
Why are there two SMILES formats?
SMILES (Connectivity) is a simplified version (no stereochemistry). SMILES (Full) includes all atoms, bonds, and stereochemistry. Both are useful depending on your needs.
How does the search suggestion (autocomplete) work?
As you type, the app uses PubChem’s official autocomplete service to show real compound names in real time — just like Google. Click any suggestion to instantly search it.
Is my Gemini API key safe?
Yes. The key is stored only in your browser’s localStorage and is never sent to any server except Google’s official Gemini API. We never see or store it.
Can I use ChemSearch offline?
No. The app needs internet access to fetch data from PubChem, Wikipedia, and optionally Gemini. Once a compound is loaded, most information stays visible even if you lose connection.
How can I send feedback or report a bug?
Click the blue floating “Feedback” button in the bottom-right corner. Your message goes directly to the developer via Formspree.
Why does Wikipedia sometimes say “description not available”?
Wikipedia pages must have an exact title match. The app automatically converts PubChem names to title case, but some compounds (especially salts, complexes, or very new ones) don’t have a Wikipedia page yet.
Can I search using a CAS number or InChI Key?
Yes! The search box accepts CAS numbers, InChI Keys, and most common synonyms. PubChem’s backend handles the resolution automatically.
Why does the elemental composition bar sometimes not add up to exactly 100%?
It’s due to rounding to one decimal place. The actual calculation uses precise atomic weights — the total is always 100% before rounding.
Why does the typewriter effect only appear on AI descriptions?
It’s a deliberate design choice to make AI-generated text feel more dynamic and engaging. PubChem and Wikipedia descriptions load instantly, so no animation is needed.
Does the app support isotopes, salts, or charged species?
Yes. PubChem handles most isotopes, hydrates, salts, and charged molecules. Just search with the correct name or formula (e.g. “D2O”, “NaCl”, “sulfate ion”).
Is my search history or API key shared with anyone?
No. Everything is stored only in your browser’s localStorage. Nothing is sent to any server except the official PubChem and Gemini APIs when needed.
Why is the InChI string sometimes extremely long?
Complex molecules with many rings, branches, or stereocenters produce longer InChI strings. This is normal — it contains complete structural information.