Lumen - Periodic Table

Lumen is a periodic table app for people who want to understand chemistry, not just memorise it. The home screen is the table — but every interaction is built to surface the patterns underneath. Tap “Atomic radius” and the cells re-color into a violet gradient with arrows showing how the trend grows down columns and shrinks across rows. The same goes for electronegativity, ionization energy, and metallic character. Once you’ve watched it animate twice, you read the periodic table differently. Twenty short lessons teach the families and the trends. Reading the table starts with rows, columns, and the four blocks. Then alkali metals, halogens, and the noble gases — what they share, why they react the way they do. Then four trend tracks (radius, electronegativity, ionization energy, metallic character) that each unpack the pattern, the why, and how to predict it. Each lesson is four to five minutes. Wrong answers feed a small spaced-repetition queue you clear on a coffee break the next morning. Seven tools beyond the table. An equation balancer that takes any reaction you can type and returns the smallest whole-number coefficients — then works the stoichiometry from a mass you supply. A molar mass calculator with a custom chemistry keyboard (no more hunting through the system keyboard for capital letters). A gas law solver that rearranges for whichever variable you leave blank. Compare mode — pick two to four elements and see them on a radar chart with an auto-generated caption. A 3D orbital viewer you can spin with your finger. A build-a-compound sandbox that tells you what you’ve made. An isotope explorer with humanised half-lives (“4.5 billion years” beats “1.4×10¹⁷ seconds”). Built honestly. Lumen is offline-first — every element, lesson, and isotope ships in the app. No accounts, no subscriptions, no tracking. Your chemistry stays on your device: searches, favorites, lesson progress, and typed formulas are never transmitted. Analytics is anonymous and off unless you turn it on. The full periodic table, every element’s detail page, the trend goggles, search, favorites, today-in-chemistry, the daily review queue and the first five lessons are free and always open. Everything else — the other fifteen lessons, five of the tools, PDF export, unlimited equation balancing — opens for the rest of the day when you choose to watch one short video. Ads pay for all of it: a small banner at the bottom of the screen, and a full-screen ad between activities — after you finish a lesson or a review, never during one. Every ad is non-personalised.