About
A sandbox where chemistry behaves, and says how sure it is.
Valence is for learners, teachers and curious people who want to play with real chemistry rather than watch a cartoon of it.
Mission
What you see is what the physics produces.
Most chemistry software either draws molecules from a template or animates a reaction someone scripted. Valence does neither. Atoms carry their valence, compete for partners and move under the forces between them, and the molecules you see are what that physics settles into.
The aim is a laboratory where:
- everyday chemistry behaves correctly, and nothing unphysical forms;
- every number is measured against a reference, and labelled with the model that made it;
- the limits are visible instead of hidden.
Where the model is wrong, the app says so, and so does this site. A labelled approximation is more scientifically serious than an unlabelled one.
The name
Why “Valence”.
Valence is the number of bonds an atom can make. In Valence’s force field, every atom has one and competes for partners. Nothing in the code names a molecule, so the name describes the core idea.
Who and how
Arda Yıldız, building with Claude.
Valence is Arda Yıldız’s project. Arda sets the direction and decides what ships; Claude, Anthropic’s model working in Claude Code, is the main engineer.
The working rules are strict, and they’re the reason the numbers on this site can be trusted:
- Plan before code. Every change is written up first: what it should do and how it will be measured.
- Measure, then decide. A change is kept or reverted on its measurements against reference data, not on how it looks.
- Write down the misses. Failed experiments and known errors are recorded with the same care as successes.
- 290
- commits between 8 and 27 September 2026
- 1,414
- automated tests passing at the last full run
- 0.5.0
- latest release, 18 September 2026
Built with TypeScript, Electron, React and Three.js.
The icon
The icon is not a drawing.
It’s a real electron cloud: one of hydrogen’s orbitals, rendered by the app from the Schrödinger equation. The one beside this text is computed live in your browser. Drag it around.
drag to rotate
Contact
Write to Arda.
Questions, early access, press or partnerships: one inbox.