Lesson 5.1.2.2

5.1.2.2 Development of the periodic table Quiz: AQA Combined Science, Unit 8

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.1.2.2, Development of the periodic table: 20 multiple choice questions for the AQA GCSE Combined Science (8464), Unit 8: Atomic structure and the periodic table, written with Revision Ninja.

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The 20 questions

  1. What did early scientists initially use to classify and arrange elements?

    • Proton numbers
    • Electron shells
    • Reacticity with water
    • Atomic weights

  2. Why did Mendeleev leave gaps in his early periodic table?

    • For heavy isotopes
    • For known compounds
    • For undiscovered elements
    • For radioactive atoms

  3. Why did early periodic tables sometimes place elements in the wrong groups?

    • Atomic weight order
    • Proton number order
    • Density measurements
    • Electron shell size

  4. Which discovery explained why the atomic-weight order was not always correct?

    • Isotopes
    • Noble gases
    • Alpha particles
    • Electrons

  5. What did Mendeleev do with gaps in his early periodic table?

    • Ignored them
    • Filled randomly
    • Left gaps
    • Deleted rows

  6. How are scientific ideas like Mendeleev's table tested and validated?

    • Using predictions
    • Mathematical proof
    • Random guessing
    • Ignoring anomalies

  7. Before protons, neutrons and electrons were known, scientists classified elements by:

    • Electron shells
    • Mass numbers
    • Atomic weights
    • Atomic numbers

  8. Why was the discovery of Mendeleev's predicted elements important?

    • Disproved atomic weights
    • Refuted his theory
    • Supported his table
    • Created new isotopes

  9. Finding an element that matches a predicted table gap demonstrates what?

    • A failed scientific model
    • Random atomic variation
    • Constant mass values
    • Evidence supporting a prediction

  10. What can testing a scientific prediction do to a new idea?

    • Support or refute
    • Only prove it
    • Only disprove it
    • Always replace it

  11. When properties did not fit atomic weight order, what did Mendeleev do?

    • Changed element order
    • Created new isotopes
    • Ignored the element
    • Removed the element

  12. Why was Mendeleev leaving gaps in his periodic table scientifically useful?

    • Removed all isotopes
    • Allowed testable predictions
    • Proved atomic weight
    • Created noble gases

  13. Which discovery explained why ordering elements strictly by atomic weight sometimes failed?

    • Protons
    • Isotopes
    • Electrons
    • Neutrons

  14. What were the empty spaces left in Mendeleev's periodic table?

    • Calculation errors
    • Isotope variations
    • Undiscovered elements
    • Radioactive decay

  15. How did the early periodic table successfully develop over time?

    • Strict mathematical formulas
    • Immediate perfection
    • Successive experimental refinements
    • Random guessing

  16. What property of an atom determines its fixed identity in the modern table?

    • Neutron mass
    • Proton number
    • Electron shell size
    • Atomic weight

  17. What did the successful discovery of Mendeleev's predicted elements support?

    • Isotope mass data
    • The scientific model
    • Proton number theory
    • Atomic weight order

  18. How are elements arranged in the modern periodic table?

    • Atomic number
    • Neutron count
    • Discovery date
    • Atomic weight

  19. What does it mean to refute a scientific hypothesis?

    • Publish the results
    • Prove it correct
    • Show it incorrect
    • Measure its mass

  20. Why did average atomic weights cause anomalies in early periodic tables?

    • Isotope mixtures
    • Neutron decay
    • Proton gain
    • Electron loss

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