Home · A-Level Chemistry 9701 · Transition elements · Physical properties of transition elements · Practice
A2 · Practice questions · Physical properties of transition elements

Fill the 3d subshell.

Six original Cambridge-style questions on transition element configurations and properties.

Original questions All questions on this page are original work, written in the Cambridge AS & A Level style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Keep these straight

Definition, configurations, properties.

01
Recall
[3 marks]

Write full electronic configurations for (a) V, (b) V3+, (c) Co2+.

  • (a) 1s22s22p63s23p63d34s2. ✓
  • (b) 1s22s22p63s23p63d2 (4s electrons removed first, then one 3d). ✓
  • (c) 1s22s22p63s23p63d7. ✓
02
Explain
[3 marks]

Scandium and zinc are d-block elements. Explain why neither is a transition element, while copper is.

  • A transition element forms one or more stable ions with an incomplete d subshell. ✓
  • Sc forms only Sc3+, [Ar], with no d electrons; Zn forms only Zn2+, [Ar]3d10, a full d subshell. ✓
  • Cu forms Cu2+, [Ar]3d9, an incomplete d subshell, so copper is a transition element. ✓
03
Explain
[2 marks]

Explain why the copper atom has the configuration [Ar]3d104s1 rather than [Ar]3d94s2.

  • The 3d and 4s energies are very close. ✓
  • A completely filled 3d subshell is especially stable, so one 4s electron occupies 3d instead. ✓
04
Explain
[3 marks]

The first ionisation energies of Ti to Cu lie between 650 and 760 kJ mol−1. Explain why they are so similar.

  • Across the series the nuclear charge increases by one each time. ✓
  • The extra electron goes into the inner 3d subshell, which shields the outer 4s electrons. ✓
  • So the attraction for the 4s electron (the one removed) increases only slightly, and the ionisation energies change little. ✓
05
Analysis
[2 marks]

How many unpaired electrons are present in (a) Fe2+ and (b) Cr3+? Show your reasoning.

  • (a) Fe2+ is 3d6: one pair plus four single electrons, so 4 unpaired. ✓
  • (b) Cr3+ is 3d3: three single electrons in separate orbitals, so 3 unpaired. ✓
06
Recall
[3 marks]

State three chemical properties typical of transition elements, giving an example of each.

  • Variable oxidation states: iron forms Fe2+ and Fe3+; manganese forms +2 to +7. ✓
  • Catalytic activity: iron in the Haber process; V2O5 in the Contact process. ✓
  • Coloured compounds and complex ions: [Cu(H2O)6]2+ is pale blue. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.