Definition: Mixture of two or more salts that combine to form a new compound.
Dissociation in water: When mixed in water, ions separate just like humans split apart in embarrassment.
Example: Potash alum (KAl(SO4)2.12H2O)
Dissociates into potassium ion (K⁺), aluminum ion (Al³⁺), and sulfate ion (SO4²⁻).
Ionic vs. Covalent Compounds
Ionic compounds dissociate in water:
Example: Potassium and aluminum ions separate in solution.
Covalent compounds do not dissociate similarly.
Coordination Complexes
Definition: A complex containing a central metal atom/ion and surrounding ligands.
Example: Potassium ferrocyanide (K4[Fe(CN)6])
Components:
Coordination Sphere: Contains the central atom and its ligands (the complex ion).
Spectator Ion: Ions outside the coordination sphere that do not participate in coordination.
Coordination Bonds
Coordinated bonds form when both electrons come from one atom (the donor) to another (the acceptor).
Ligand Types:
Monodentate: Ligands providing one lone pair (e.g. NH3).
Bidentate: Ligands providing two lone pairs (e.g. oxalate).
Polydentate: Multiple lone pairs donating.
Examples of Ligands and their Properties
Homoleptic Complex: All ligands are of the same type.
Heteroleptic Complex: Different types of ligands are present.
Oxidation States and Calculation
Calculating oxidation states for transition metals is crucial in these complexes.
Example: For [Co(NH3)6]Cl3, Co oxidation state = +3.
Effective Atomic Number (EAN)
EAN = Atomic Number of the central metal atom + Twice the number of coordinate bonds.
When EAN equals the number of electrons in the nearest noble gas, the complex is considered stable.
Applications of EAN
Determines the reducing and oxidizing ability of compounds.
Example: Vanadium and Manganese modes demonstrate relation with EAN and stability (e.g. V = typically reducing, Mn = typically oxidizing in certain states).
Coordination Number
Coordination number tells how many bonds are formed between ligands and central atom.
Example: In [Fe(CN)6]4- , the coordination number is 6.
Summary
Coordination compounds are fundamental not only for theoretical aspects but also practical applications in chemistry and biology.
Conclusion
Importance of practice in solving numerical problems and understanding concepts in coordination chemistry.
Need for familiarity with IUPAC naming and stoichiometry.