Summary Transition Metals: Complex Ions, Ligand Substitution & Redox Reactions – A-Level/IB Chemistry Notes

This document provides detailed A-Level/IB Chemistry notes on transition metals, focusing on their electronic configuration, complex ion formation, isomerism, and characteristic reactions. Key Topics Covered: Definition & Properties of Transition Metals: Criteria: Forms at least one ion with a partially filled d-orbital (excludes Sc³⁺ and Zn²⁺). Characteristics: Forms colored compounds (e.g., Cu²⁺ → blue, Fe³⁺ → orange-brown). Acts as catalysts (e.g., Fe in Haber process). Exhibits variable oxidation states (e.g., Fe²⁺/Fe³⁺, Cr³⁺/Cr₂O₇²⁻). Complex Ions & Ligands: Ligands: Molecules/ions donating lone pairs (e.g., H₂O, NH₃, Cl⁻). Shapes: Octahedral (e.g., [Cu(H₂O)₆]²⁺), square planar (e.g., cisplatin), tetrahedral. Isomerism: Cis-trans isomers (e.g., cisplatin vs. transplatin; cis binds DNA for chemotherapy). Optical isomers (non-superimposable mirror images). Reactions: Ligand Substitution: [Cu(H₂O)₆]²⁺ (pale blue) + NH₃ → [Cu(NH₃)₄(H₂O)₂]²⁺ (deep blue). [Co(H₂O)₆]²⁺ (pink) + Cl⁻ → [CoCl₄]²⁻ (blue). Precipitation: Colors of hydrated ions (e.g., Fe²⁺ → green, Mn²⁺ → light brown). Redox: Fe²⁺ ⇌ Fe³⁺ + e⁻. Disproportionation of Cu⁺ (2Cu⁺ → Cu²⁺ + Cu). Biological & Industrial Applications: Hemoglobin: Fe²⁺ complex with a tetradentate ligand (irreversible CO binding). Cisplatin: Anti-cancer drug (square planar geometry). Why This Document is Useful: Exam-Focused – Covers complex ion structures, isomerism, and redox trends. Color-Coded Reactions – Helps memorize ion colors and ligand substitutions. Real-World Context – Links to medicine (cisplatin) and biology (hemoglobin). Structured & Concise – Ideal for quick revision before tests. Perfect for students mastering transition metal chemistry or teachers preparing lessons on coordination compounds! ️