AQA A-Level Chemistry Paper 3, 2017: Question 7

✅ Correct Answer: C

Statement C is false (and therefore the correct answer to the question):

"A ligand accepts a pair of electrons from a transition metal"

By definition, a ligand is an electron-pair donor (a Lewis base), not an acceptor. The transition metal ion acts as the electron-pair acceptor (a Lewis acid).

💡 Key Knowledge

• Ligand: An atom, ion, or molecule that donates a lone pair of electrons to a central metal atom or ion to form a coordinate (dative covalent) bond.
• Complex: A central metal atom or ion surrounded by ligands bonded via coordinate bonds.
• Transition Metal Characteristics:
  • Variable oxidation states (e.g. Fe²⁺ / Fe³⁺)
  • Formation of coloured ions
  • Catalytic behaviour
  • Complex formation

🧠 Option Breakdown

• A (True statement): Transition metals typically form coloured ions and complexes due to d-orbital splitting and d–d electron transitions.
• B (True statement): Transition metals have 4s and 3d electrons of similar energies, allowing them to exhibit multiple stable oxidation states.
• C (FALSE statement): Reverses the direction of electron transfer. Ligands donate lone pairs; metal ions accept them.
• D (True statement): This matches the standard specification definition of a complex.

❌ Common Errors & Traps

• Misreading "NOT": Rushing students miss the bold word not, spot Statement A (which is completely true), and instantly select it. Always circle the word NOT when scanning exam papers!
• Confusing Lewis Acids and Bases: Mixing up donor vs acceptor roles. Remember: Ligand = Lone pair Provider (both start with 'L').