Shapes of complex ions and isomerismAQA A-Level Chemistry: Mind map

Exam questions on Shapes of complex ions and isomerism

1. A student compares the shapes of four complex ions: [Ni(H₂O)₆]²⁺, [CoCl₄]²⁻, [Ag(NH₃)₂]⁺ and [Pt(NH₃)₂Cl₂].
   Explain why [Ni(H₂O)₆]²⁺ is octahedral but [CoCl₄]²⁻ is tetrahedral.2 marks
2. The octahedral complex ion [Co(NH₃)₄Cl₂]⁺ exists in two forms, one green and one violet. The complex ion [Ni(en)₃]²⁺, where en is the bidentate ligand H₂NCH₂CH₂NH₂, also exists in two forms.
   State what is meant by optical isomers and explain why [Ni(en)₃]²⁺ shows optical isomerism.2 marks
3. Platinum(II) forms the neutral complex Pt(NH₃)₂Cl₂, which has a square planar shape and exists as two isomers. One of them, cisplatin, is used as an anticancer drug.
   State the shape of the complex, its co-ordination number and the arrangement of the chloride ligands in cisplatin.3 marks