Molecular Scrabble — spell real chemical formulas on a Scrabble-style board. Read the instruction book below, play with friends on one device or at an online table, or practise alone in Solitaire, with an AI chemist checking every formula.
Molecular Scrabble adapts classic crossword-tile mechanics to real chemistry. Instead of spelling words, you spell chemical formulas — real, charge-balanced compounds and elements — by laying element tiles across a 15×15 board. Score points for atomic weight, board bonuses, and clever crossings, exactly like a word-game, just built from the periodic table instead of the alphabet.
Score the most points by building valid molecular formulas on the board using your element tiles — left to right or top to bottom, just like Scrabble words.
A valid play is any sequence of element tiles that forms a real, recognized chemical formula — a compound, ion, or elemental form that actually exists and is charge-balanced. Subscripts are written by repeating a tile: H₂O is played as H · H · O.
A formula must use at least two tiles to score on its own — a lone element symbol only counts when it extends an existing formula, the same two-letter minimum classic Scrabble uses.
120 tiles in the box: common, light elements are worth less and are more plentiful; rare or heavy elements are worth more and appear only once or twice. Four blank Wild Isotope tiles stand in for any element for zero points.
| Symbol | Element | Points | Count |
|---|
The board uses the standard Scrabble layout of premium squares — they apply only the turn a tile is first placed on them.
Optional house rule — Biology Bonus: +5 points for any formula found naturally in the human body (H₂O, CO₂, NaCl, C₆H₁₂O₆…).
Setup & TurnsMix all tiles in the bag. Each player draws 7 tiles onto their rack. Randomly determine turn order and keep the Master Molecule Reference Card visible.
Play a formula (the first must cross the centre star), exchange any number of tiles for new ones from the bag, or pass. Every new formula you form — including crossings — must be valid.
Sum tile values, apply letter bonuses first, then word bonuses. Using all 7 tiles in one turn earns a +15 Full Reaction bonus.
The game ends when the bag is empty and one player empties their rack, or when every player passes twice in a row. Final scores subtract each player's unused tile values.
Play alone against the bag. The board, tiles, formula rules and scoring are the same as the main game; the challenge is to score as much as you can from one bag of 120 tiles.
Draw 7 tiles. There are no opponents and no turn timer. Your first formula must cover the centre star.
Place formulas exactly as in the main game, crossings included. The +15 Full Reaction bonus still applies. Refill to 7 tiles after every play.
You may exchange tiles three times per game while the bag still has tiles. There are no passes: if you are stuck and out of swaps, end the game.
Use every tile in the bag and on your rack for a +25 Clean Bench bonus. If you end early, the value of your unused rack tiles is subtracted.
Your final score earns a rank:
VariantsShare one phone, tablet or laptop and take turns. When your turn ends, the screen hides your tiles and asks you to pass the device on; the next player taps to reveal their own rack. The rules are the main game's: exchange or pass whenever you like, the game ends when the bag is empty and someone empties their rack (they collect everyone else's leftover tile values) or when every player passes twice in a row. No Claude account is needed. Switch on Theory Mode and the built-in valency rules referee even when the AI chemist isn't available.
Theory ModeIn Theory Mode a formula doesn't have to exist in any lab. It is valid if you could draw a neutral structure on paper in which every atom's valency is satisfied (or if it's a real substance anyway, such as carbon monoxide), using each element's usual valencies (carbon 4, oxygen 2, nitrogen 3 or 5, sulfur 2, 4 or 6, and so on). Tiles may also run in any element order, so ClNa is as good as NaCl.
The referee marks each accepted formula as known or hypothetical and sketches one way its atoms could bond, so the lab notebook fills up with your inventions. Formulas still need at least two tiles, and noble gases (He, Ne) can't bond to anything.
| Played | Standard | Theory | Why |
|---|---|---|---|
| H · H · O | Valid | Valid | Water: known, valencies satisfied |
| C · C · O · O | Rejected | Valid | O=C=C=O balances on paper but has never been isolated, so it scores as hypothetical |
| C · H · H | Rejected | Rejected | Carbon needs four bonds and only gets two |
| O · H · H | Rejected | Valid | Water written in an unusual order |
| Cl · Na | Rejected | Valid | Element order doesn't matter in Theory Mode |
| He · O | Rejected | Rejected | Helium forms no bonds |
| Formula | Name | Tiles needed |
|---|