Every tile is a chemical element, laid out at its real periodic-table position (period = row, group = column). A tile pops into solid colour the instant the timeline crosses that element's discovery year — antiquity's metals (gold, iron, copper, tin, lead, mercury, sulfur, carbon) are visible from the very start, since people worked with them millennia before atomic theory existed.
Three tiles do something extra: scandium, gallium and germanium appear first as a pulsing wireframe ghost the moment the clock passes 1869 — the year Dmitri Mendeleev published a periodic table with deliberate gaps, correctly predicting the mass and properties of elements not yet found. Each ghost resolves into a solid tile only when it was actually isolated (gallium 1875, scandium 1879, germanium 1886) — a direct visualization of a successful scientific prediction.
tile.state =
year < predictedYear → hidden
predictedYear ≤ year < discoveryYear → ghost (predicted, unconfirmed)
year ≥ discoveryYear → solid, coloured by era
- Year — scrub the whole timeline manually, from the Bronze Age to the present.
- Play / speed — auto-advance the clock at a chosen rate to watch the table fill in continuously.
- Milestones — jump straight to the moments historians usually cite: Mendeleev's 1869 table, the 1900 dawn of radiochemistry, and the 1945 start of purely synthetic, reactor- and accelerator-made elements.
Colour marks the era an element was actually isolated in: antiquity, early chemistry (alchemy through the 1600s), the pneumatic-chemistry 18th century, the systematic pre-periodic-law decades, the classical periodic-table era after 1869, the radioactivity/quantum era (1900–1945), and the post-war synthetic era of particle accelerators.