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Atomic Number Quiz

Match elements to their atomic numbers — the proton count that defines each element.

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Shaky on the concepts? Review Atomic Number vs Atomic Mass first, then come back.

About the Atomic Number Quiz

The atomic number is the number of protons in an atom's nucleus, and it is what actually defines an element — change it and you change the element. This quiz asks you to match elements to that number across the first few periods, reinforcing the order of the table from hydrogen (1) upward. Knowing the anchor numbers — carbon 6, oxygen 8, sodium 11, calcium 20, iron 26 — makes electron configurations and the whole layout of the periodic table much easier to reason about. Ten questions per round, three difficulty levels, with an explanation after every answer.

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