Grade 12
  1. Solid state  1.1. Classification of solids  1.2. Crystal Lattice and Unit Cell  1.3. Packing Efficiency  1.4. Density of unit cell  1.5. Imperfections in solids (point and line defects)  1.6. Electrical Properties of Solids (Conductors, Insulators and Semiconductors)  1.7. Magnetic Properties of Solids (Diamagnetic, Paramagnetic and Ferromagnetic Materials)
  2. Solution  2.1. Types of Solutions (Homogeneous and Heterogeneous)  2.2. Expressing concentration of solutions (mass %, volume %, molarity, molality, normality, mole fraction)  2.3. Solubility of solids and gases in liquids (Henry's law)  2.4. Raoult's Law and Ideal and Non-Ideal Solutions  2.5. Syndrome properties  2.6. Abnormal molar mass and Van't Hoff factor
  3. Electrochemistry  3.1. Electrochemical cells (galvanic and electrolytic cells)  3.2. Galvanic cell and EMF of the cell  3.3. Standard electrode potential and electrochemical series  3.4. Nernst equation and its applications  3.5. Conductivity and electrolytic cells (specific, molar and equivalent conductivity)  3.6. Kohlrausch's law and its applications  3.7. Batteries (primary and secondary cells)  3.8. Corrosion and its prevention
  4. Chemical kinetics  4.1. Rate of chemical reaction  4.2. Factors affecting the reaction rate (concentration, temperature, catalyst, surface area)  4.3. Order and molecularity of the reaction  4.4. Integrated Rate Equations (Zero, First and Second Order)  4.5. Half-life of a reaction  4.6. Collision theory and activation energy  4.7. Arrhenius equation and its applications
  5. Surface chemistry  5.1. Adsorption and its types (Physicosorption and Chemisorption)  5.2. Catalysis and its types (homogeneous and heterogeneous)  5.3. Colloids and their properties (Tyndall effect, Brownian motion, coagulation)  5.4. Emulsions and gels  5.5. Applications of Colloids
  6. General principles and processes of separation of elements  6.1. Presence of metals and minerals  6.2. Concentration of ores (gravity separation, froth flotation, magnetic separation)  6.3. Extraction of raw metals (roasting, calcination, reduction)  6.4. Thermodynamic and electrochemical principles of metallurgy  6.5. Refining of metals
  7. P-block elements  7.1. Group 15 elements (nitrogen and phosphorus)  7.2. Group 16 Elements (Oxygen, Sulphur and their Compounds)  7.3. Group 17 Elements (Halogens and their Compounds)  7.4. Group 18 Elements  7.5. Properties and Trends in p-Block Elements  7.6. Important compounds of p-block elements (ammonia, phosphine, sulphuric acid, hydrochloric acid)  7.7. Interhalogen compounds and their applications
  8. d-block and f-block elements  8.1. General Properties of Transition Metals  8.2. Properties of Inner Transition Metals (Lanthanoids and Actinoids)  8.3. Lanthanoid and actinoid contractions  8.4. Coordination Chemistry of d-Block Elements
  9. Coordination compounds  9.1. Werner's theory and modern concepts  9.2. Coordination number and type of ligand  9.3. Nomenclature of Coordination Compounds  9.4. Isomerism (geometrical and optical) in coordination compounds  9.5. Bonding in Coordination Compounds (Valence Bond Theory and Crystal Field Theory)  9.6. Stability and applications of coordination compounds in medicine and industry
  10. Haloalkanes and haloarenes  10.1. Classification and nomenclature of haloalkanes and haloarenes  10.2. Physical and Chemical Properties of Haloalkanes and Haloarenes  10.3. Mechanism of Nucleophilic Substitution Reactions (SN1 and SN2)  10.4. Uses and environmental effects (ozone depletion, CFCs)
  11. Alcohol, phenol and ether  11.1. Structure and classification of alcohols, phenols and ethers  11.2. Preparation and properties of alcohols  11.3. Preparation and properties of phenol  11.4. Preparation and properties of ethers  11.5. Chemical Reactions and Uses
  12. Aldehydes, ketones and carboxylic acids  12.1. Structure and nomenclature in aldehydes, ketones and carboxylic acids  12.2. Preparation and properties of aldehydes and ketones  12.3. Chemical reactions in aldehydes, ketones and carboxylic acids (nucleophilic addition, oxidation and reduction)  12.4. Preparation and Properties of Carboxylic Acids  12.5. Chemical Reactions and Uses of Carboxylic Acids
  13. Nitrogen-containing organic compounds  13.1. Amines (classification, structure, basicity)  13.2. Preparation and properties of amines  13.3. Reactions of Amines (Diazotization, Carbylamine Reaction)  13.4. Diazonium salts and their applications in paint industry
  14.1. Carbohydrates (classification and properties)  14.2. Proteins (Structure and Function)  14.3. Enzymes (Mechanism and Function)  14.4. Nucleic acids (DNA and RNA)  14.5. Vitamins and hormones
  15. Polymer  15.1. Classification of Polymers (Addition, Condensation, Copolymers)  15.2. Types of polymerization (free radical, ionic, condensation)  15.3. Important Polymers and Their Uses  15.4. Biodegradable and non-biodegradable polymers
  16. Chemistry in Everyday Life  16.1. Drugs and their classification (analgesics, antipyretics, antibiotics, antacids)  16.2. Chemicals in food and cosmetics (preservatives, artificial sweeteners, antioxidants)  16.3. Cleaning agents and detergents (soaps, synthetic detergents, surfactants)  16.4. Environmental Chemistry (Pollution, Green Chemistry, Sustainable Chemistry)

Grade 12 → Coordination compounds ↓


Werner's theory and modern concepts


In the world of chemistry, coordination compounds hold a significant place due to their complexity and utility. Swiss chemist Alfred Werner proposed a revolutionary theory in the early 20th century that laid the foundation for modern coordination chemistry. This theory is important for understanding how different elements can form complex structures. The study of coordination compounds involves understanding how molecules form, interact, and can be applied in a variety of fields ranging from industrial applications to biological systems.

Werner's theory of coordination compounds

Alfred Werner presented a theory in 1893 that challenged the existing fundamental concepts of valency. The main idea of Werner's theory is that the behavior and structure of coordination compounds cannot be explained using simple ionic or covalent bonding. Take a closer look at the key aspects of Werner's theory:

Key concepts

  • Primary and secondary valency: Werner proposed that metal ions exhibit two types of valency:
    • Primary valency: This is the oxidation state of the metal ion and is completed by ions having a charge (positive or negative). For example, the primary valency of Cr in CrCl 3 is +3.
    • Secondary valency: This is the coordination number of the metal and represents the number of atoms directly bonded to the central metal ion. These are usually neutral molecules or ions, such as NH 3 or Cl -, respectively.
  • Coordination number: The coordination number is the number of ligand donor atoms bonded to the central atom. In Werner's time, it was usually found to be 4 or 6.
  • Geometry of coordination compounds: Werner suggested that coordination compounds could form spatial geometries. He identified octahedral, tetrahedral, and square planar arrangements.

Werner's experiments

Let us discuss a specific series of experiments that helped Werner formulate his theory. Consider the compound CoCl 3 .6NH 3. Werner proposed three different forms for this chemical compound: [Co(NH 3) 6]Cl 3, [CoCl(NH 3) 5]Cl 2, and [CoCl 2(NH 3) 4]Cl. This shows that the molecule can exhibit different arrangements with different numbers of coordinated and anionic chlorine atoms.

When these compounds were dissolved in water, different numbers of ions were produced, which Werner measured through conductivity experiments. This difference in the number of ions supports the different proposed structures.

Compound 1 Compound 2

Modern concepts of coordination chemistry

Modern coordination chemistry has evolved considerably since Werner's time due to the development of quantum mechanics and advanced analytical techniques. Here are some modern concepts that build on Werner's foundation:

Crystal field theory (CFT)

Crystal field theory provides a simple model for understanding how metal ions interact with ligands. According to CFT, the electrostatic interaction between ligands and metal ions causes a splitting in the d-orbital energy. This splitting produces:

  • t 2g orbitals: lower energy set
  • e g orbitals: higher energy set

The energy difference between these orbitals affects the properties of the compound, such as its colour and magnetic behaviour.

Ligand field theory (LFT)

Ligand field theory combines aspects of CFT and molecular orbital theory (MOT) to provide a more comprehensive understanding of coordination compounds. LFT provides insight into both bonding and electronic structure, looking at how different ligands can affect the hybridization and geometry of a compound.

Valence bond theory (VBT)

Valence bond theory includes the concept of hybridization, where atomic orbitals of metal ions mix to form hybrid orbitals. These hybrid orbitals can bond with ligand orbitals to form coordination complexes. For example, nickel undergoes sp 3 hybridization in the complex [Ni(CN) 4] 2-.

Metal Ligand 1 Ligand 2

Example: coordination compounds in biological systems

Coordination compounds are not limited to industrial applications only. In biological systems, they play important roles. For example:

  • Hemoglobin: The iron-centered coordination complex in hemoglobin helps transport oxygen in the blood.
  • Chlorophyll: At the center of the chlorophyll molecule is a magnesium ion, coordinated with nitrogen atoms.

Conclusion

Werner's theory laid a solid foundation, allowing future researchers and chemists to explore coordination compounds and find their applications. Modern theories such as crystal field theory and ligand field theory have expanded our understanding and applications. Thus, coordination chemistry remains an integral field that connects various chemical concepts and offers diverse practical applications.


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