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Practice · Chemistry · 2025 syllabus · S3.1

IB Chemistry S3.1 The periodic table: practice questions

12 exam-style questions on S3.1 The periodic table, SL and HL, 5 marked HL: 8 multiple choice, 1 data-based and 3 structured. Each one comes with the mark scheme, a model answer and the reasoning behind every mark. Free with your email.

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S3.1-01 · Paper 1A style · multiple choice · 1 mark

Radius of sulfur species

Which list puts these sulfur species in order of increasing radius? [1]

  1. S2−, S, S4+, S6+
  2. S6+, S4+, S, S2−
  3. S, S2−, S4+, S6+
  4. S4+, S6+, S2−, S
Show the answer and the reasoning

Answer: B. B is correct. All four have 16 protons. Removing electrons leaves fewer electrons held by the same nuclear charge, and the outer shell is lost, so positive ions are smaller, the more so the higher the charge. Adding electrons increases repulsion between them, so S2− (184 pm) is larger than the atom (104 pm). A is the decreasing order. C and D mix up the effect of charge.

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The 12 questions in S3.1

  1. S3.1-01 Radius of sulfur speciesPaper 1A style · multiple choice · 1 mark
  2. S3.1-02 Atomic radius down a groupPaper 1A style · multiple choice · 1 mark
  3. S3.1-03 Most vigorous metal–halogen pairPaper 1A style · multiple choice · 1 mark
  4. S3.1-04 Most acidic oxidePaper 1A style · multiple choice · 1 mark
  5. S3.1-05 Atoms in the +5 oxidation statePaper 1A style · multiple choice · 1 mark
  6. S3.1-06 Typical transition element propertiesPaper 1A style · multiple choice · 1 mark · HL
  7. S3.1-07 Which ion is colouredPaper 1A style · multiple choice · 1 mark · HL
  8. S3.1-08 What we see in a yellow complexPaper 1A style · multiple choice · 1 mark · HL
  9. S3.1-09 Nickel ions by colorimetryPaper 1B style · data-based · 7 marks · HL
  10. S3.1-10 Colour of a cobalt complexPaper 2 style · structured question · 6 marks · HL
  11. S3.1-11 Rubidium and its groupPaper 2 style · structured question · 5 marks
  12. S3.1-12 Radii across period 3Paper 2 style · structured question · 5 marks

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Every Biology and Chemistry question here is original, written for practice in the style of the papers set since the 2025 syllabus, with invented data. Developed independently from the International Baccalaureate Organization, which has not endorsed it. Found a mistake? Email vytis@limeadmissions.com with the question id.