Atomic number quiz: find each element’s number
Practice recalling the atomic number of each element, the number of protons in its nucleus. Knowing atomic numbers helps you place elements on the table quickly and gives you the electron count you need for electron configurations.
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How it works
Questions alternate between picking the atomic number of a named element and naming the element with a given number. Every answer gets instant feedback, and your best score is saved in your browser. Choose the first 20, the first 36 or all 118 elements before you start.
Play it three ways: a classic round of 10 questions, a 60-second speed round (25 right answers earns a star), or survival, where you keep going until you miss three.
Tips
- Use the noble gases as landmarks: helium 2, neon 10, argon 18, krypton 36, xenon 54, radon 86 and oganesson 118.
- Count on from the nearest noble gas: the next element starts a new period in group 1, so potassium is 19 and rubidium is 37.
- Neighbors in a period differ by one, so if you know oxygen is 8, you also know nitrogen is 7 and fluorine is 9.
- The atomic number is also the number of electrons in a neutral atom, the starting point for its electron configuration.