Transition metals, configurations and oxidation statesEdexcel International A Level Chemistry: Subtopic test

1. 1
   A technician prepares aqueous solutions of salts of Period 4 d-block metals for a titration practical and records the electronic configurations of the metal atoms and ions involved.

   (a)

   Which ion has the electronic configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶?

   [1 mark]

   • AMn²⁺
   • BFe²⁺
   • CCo²⁺
   • DNi²⁺

   (b)

   Which is the ground-state electronic configuration of a chromium atom?

   [1 mark]

   • A[Ar] 3d⁴ 4s²
   • B[Ar] 3d⁶
   • C[Ar] 3d⁵ 4s¹
   • D[Ar] 3d⁴ 4s¹

   (c)

   Deduce the full electronic configurations of an iron atom and of an Fe³⁺ ion.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Scandium, copper and zinc are all Period 4 elements in the d-block. Scandium forms only the Sc³⁺ ion in its compounds and zinc forms only the Zn²⁺ ion. Copper forms both Cu⁺ and Cu²⁺ ions.

   (a)

   Which statement explains why scandium is not classed as a transition metal?

   [1 mark]

   • AScandium atoms have no 4s electrons
   • BScandium atoms have a full 3d sub-shell
   • CScandium does not form any ions
   • DThe Sc³⁺ ion has no electrons in the 3d sub-shell

   (b)

   Which is the electronic configuration of a Cu²⁺ ion?

   [1 mark]

   • A[Ar] 3d⁹
   • B[Ar] 3d¹⁰
   • C[Ar] 3d⁹ 4s²
   • D[Ar] 3d⁸ 4s¹

   (c)

   Explain why zinc is not classed as a transition metal.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Manganese forms compounds in a wide range of oxidation states. A chemist has samples of manganese(IV) oxide, MnO₂, potassium manganate(VI), K₂MnO₄, and potassium manganate(VII), KMnO₄.

   (a)

   Deduce the oxidation number of manganese in MnO₂, in K₂MnO₄ and in KMnO₄.

   [3 marks]

   (b)

   Explain, with reference to the electronic configuration of a manganese atom, why manganese can show oxidation numbers from +2 up to +7.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A chemist is investigating Period 4 elements. Vanadium forms compounds with oxidation numbers +2, +3, +4 and +5, whereas calcium forms compounds only with oxidation number +2. She also considers these ions: Sc³⁺, Ti³⁺, Mn²⁺, Cu⁺, Cu²⁺ and Zn²⁺.

   (a)

   Explain why vanadium has several oxidation numbers but calcium has only one.

   [6 marks]

   (b)

   Deduce the electronic configuration of each ion, in the form [Ar] 3dⁿ, and hence deduce which of the elements scandium, titanium, manganese, copper and zinc are transition metals.

   [6 marks]

   Total for question 4: 12 marks

End of questions