Support
Questions, bug reports or ideas for new quiz questions are all welcome.
Email the developer
Include your device model and iOS or iPadOS version if you're reporting a problem. Replies usually arrive within two working days.
Frequently asked questions
When does a new question appear?
A new daily question unlocks every day. Everyone on the same level gets the same question on the same day, and the Home screen shows a countdown to the next one once you've answered.
How do I change the difficulty?
Pick Beginner, Normal or Expert when you first open the app, or change it any time in Settings. Higher levels mostly ask questions at that level, with some easier ones mixed in. Once you've started answering, a new level begins with the next day's question. After a run of correct answers, the Home screen offers to move you up.
How do streaks and card packs work?
A correct answer on the first try wins 2 cards, and on the second try 1. Keep a streak going and the first-try pack grows: 3 cards at 7 days, 4 at 15 days and 5 at 30 days. A correct second try still extends your streak.
What is a streak freeze?
A streak freeze protects your streak on a day you miss or get wrong. You earn one for every 7 days in a row and can hold up to 2, and each one covers a single day.
I answered wrong. Can I try again?
Yes, once. A wrong first answer is crossed out and you get a second try, which wins 1 card if it's right. If both answers are wrong, you'll see the explanation and a new question arrives tomorrow.
My progress isn't showing on my other device.
Progress syncs through iCloud. Check that both devices are signed in to the same Apple Account and that iCloud is turned on for Radionuclide Cards in Settings. Syncing can take a few minutes after you open the app.
Why can't I see the chart in augmented reality?
AR needs a device that supports ARKit. On other devices the chart opens in 3D instead, and you can still rotate it and tap any column.
Why don't I see the Apple Intelligence explanations?
Explanations are written on your device by Apple Intelligence, so they need a supported device with Apple Intelligence turned on in Settings.
Where does the nuclear data come from?
From the IAEA Nuclear Data Section: ENSDF for decay data and the Atomic Mass Evaluation (AME) for atomic masses. If you spot a value that looks wrong, please email the nuclide and the field, and it will be checked against the source.
Which languages are available?
English, German, Spanish, French and Italian. The app follows your device language, and this website follows your browser language. You can switch the website language in the menu at the top of the page.