Chemistry Lab
An interactive, intuition-first study site for AP Chemistry: 3D molecules you can spin, particle simulations you can squeeze and heat, worked examples, randomized practice, and review tools. It is a sibling of Mechanics Lab and shares its engine and design.
The whole site is one HTML file (index.html), built from a small src/ folder. Open index.html in a browser, or serve the repo with GitHub Pages.
Unofficial study aid. Not affiliated with the College Board.
Use it to study, not on graded work. Don't use this site on homework you submit, in labs, or during quizzes and exams.
Layout
build.py assembles src/ into index.html (checks JS syntax and id clashes)
src/
head.html shell_top.html shell_bottom.html page shell: fonts, drawers, side menu
css/engine.css chem.css design system (shared with Mechanics Lab) + chemistry additions
js/core.js helpers, particles/confetti, the 3D viewer (view3d)
js/registry.js chemlib.js roster/registries, atoms, molecules, the balloon (VSEPR) model
js/practice.js teach.js ... problem cards, FRQ scoring, the teaching layer, router, theme, search
modules/<id>.html + <id>.js one view and one script per module
review/*.html overview, practice, which-tool, exam, mistakes, FRQ views
data/*.js periodic table data (and, later, problem and FRQ banks)
ref/eq.html sol.html equations/constants and solubility/ions reference sheets
groups.json mods.json unit order and module titles
tests/
check.js visits every view at desktop and phone width (light/dark): overflow, blank canvases, NaN text, Set-it-up buttons
flow.js end-to-end flows: practice, mistakes queue, exam builder, quiz, search, periodic table, report dialog
probdump.js prints generated samples of every practice problem so the answers can be checked by hand
audit.js stress-tests every generator (400 samples each) for NaN text, bad choices, impossible values
design.js contrast, touch-target and reduced-motion checks
A module is "built" when both src/modules/<id>.html and <id>.js exist; modules listed in groups.json without files show as "Coming soon" on the overview.
Build and test
python3 build.py # writes index.html
node tests/check.js [module ...] # needs Node and Playwright (global install)
node tests/flow.js
N=3 node tests/probdump.js # three samples of every generator
localStorage keys all start with chem- (Mechanics Lab uses kin-), so both sites can share a GitHub Pages domain. The page deliberately has no doctype and renders in quirks mode, so ids and class names match case-insensitively: never use two names that differ only by case (build.py checks ids).
Reporting a problem
Every module and practice problem has a Report an issue link that opens a pre-filled GitHub issue. Issues go to the shared Intulab feedback tracker, labelled course:chem. You can also open one directly.
The More labs link in the side rail goes to the Intulab landing page. Visits are counted anonymously with GoatCounter (no cookies), shared with the other Intulab sites.
