Puzzle Archive — click any date to load that day's puzzle

How to Play

  1. Read each clue — compounds are given in words, not formulas.
  2. Find each compound's formula in the reference table below.
  3. Enter coefficients (1–9) so both sides of each reaction balance — equal atoms on each side.
  4. Orange cells are shared between two reactions. One number serves both.
  5. Press Check when every reaction is balanced.
  6. Expert only: formula labels are hidden — type each compound's formula in the dashed cell above its coefficient.

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Compound Reference

NameFormula

⚗️ Element Reference

Common elements used in chemistry. The charge shown is the most common oxidation state(s).

Positive Negative Variable Noble / None
🔗 Open Full Interactive Periodic Table (ptable.com)