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Atomic structure worksheet: protons, neutrons and electrons

Students practise counting protons, neutrons and electrons from atomic and mass numbers, comparing isotopes and finding the charge of ions. The worksheet uses multiple choice, fill in, matching, ordering and sorting items for grade 10 chemistry.

By Edform · Chemistry · Grade 10 · Published Nov 3, 2026 · New

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Questions

  1. An atom has atomic number 15 and mass number 31. How many neutrons does it have?
  2. Which number tells you which element an atom is?
  3. Oxygen-16 and oxygen-18 are isotopes of oxygen. How do their atoms differ?
  4. A particle has 12 protons and 10 electrons. What is its charge?
  5. Type the missing numbers. Sodium has atomic number 11.
  6. Type the missing numbers. Sulfur has atomic number 16.
  7. Choose the correct words.
  8. Put these particles in order from the fewest electrons to the most electrons. Atomic numbers: Li 3, O 8, F 9, Ca 20.
  9. Match each isotope to its number of neutrons. Atomic numbers: C 6, O 8, Cl 17.
  10. Sort each particle by its overall charge.

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