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IB Chemistry HL 3.1.9 Hl Variable Oxidation States Questions

Use real exam questions to explain variable oxidation states, deduce first-row transition-ion configurations and justify stable ions.

Syllabus
First assessment 2025
Course
Chemistry HL
Level
HL

Exam points

  • Explain variable oxidation states in first-row transition elements from close successive ionization energies and the similar d- and s-electron energies.
  • Deduce electron configurations of first-row transition-element ions after removal of 4s then 3d electrons, preserving electron counts and sublevel order.
  • Use ionization-energy patterns and electron configurations to compare possible ions and justify which oxidation states are stable or variable.

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Study 3.1.9 (HL)—Variable oxidation states conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Chemistry HL 3.1.9 Hl Variable Oxidation States Questions question 1

[Maximum number: 3]

Beryllium is a low-density metal that is used in specialized lightweight alloys.

Iron (III) chloride also exists as a dimer in the vapour phase, but iron, unlike beryllium, is a transition element.

The first four ionization energies of beryllium and iron are shown.

Figure for Question IB Chemistry HL 3.1.9 Hl Variable Oxidation States Questions question 1 — IB Chemistry HL

One common property of transition elements is that they have variable oxidation states. Discuss, referring to the graph, why iron, but not beryllium, displays this characteristic.

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