Topics
Some Basic Concepts of Chemistry
Introduction to Analytical Chemistry
- Introduction of Analytical Chemistry
- Analysis
- Mathematical Operation and Error Analysis
- Determination of Molecular Formula
- Chemical Reactions and Stoichiometric Calculations
- Limiting Reagent
- Concentration of a Solution
- Use of Graph in Analysis
Basic Analytical Techniques
- Introduction of Some Analytical Techniques
- Purification of Solids
- Crystallisation Method
- Fractional Crystallization
- Simple Distillation Method
- Solvent Extraction
- Chromatography Method
- Chromatography Method > Adsorption Chromatography
- Chromatography Method > Partition Chromatography
Structure of Atom
Chemical Bonding
- Concept of Chemical Bonding
- Kossel-lewis Approach to Chemical Bonding - Octet Rule
- Kossel and Lewis Approach to Chemical Bonding
- Formal Charge
- Limitations of the Octet Rule
- Valence Shell Electron Pair Repulsion (VSEPR) Theory
- Valence Bond Theory (VBT)
- Molecular Orbital Theory
- Parameters of Covalent Bond
- Dipole Moment
- Resonance
Redox Reactions
Modern Periodic Table
- Introduction of Periodic Table
- Structure of the Modern Periodic Table
- Periodic Table and Electronic Configuration
- Blockwise Characteristics of Elements
- Periodic Trends in Elemental Properties
Elements of Group 1 and 2
Elements of Group 13, 14 and 15
- Electronic Configuration of Elements of Groups 13, 14 and 15
- Trends in Atomic and Physical Properties of Elements of Groups 13, 14 and 15
- Chemical Properties of the Elements of the Groups 13,14 and 15
- Carbon: A Versatile Element
- Allotropes of Carbon > Diamond
- Molecular Structures of Some Important Compounds of the Group 13, 14 and 15 Elements
- Chemistry of Notable Compounds of Elements of Groups 13, 14 and 15
States of Matter
- States of Matter
- Intermolecular Forces
- Characteristic Properties of Gases
- Gas Laws
- Ideal Gas Equation
- Kinetic Molecular Theory of Gases
- Deviation from Ideal Behaviour
- Liquefaction of Gases and Critical Constant
- Liquid State
Adsorption and Colloids
- Introduction of Adsorption
- Adsorption
- Types of Adsorption
- Factors Affecting Adsorption of Gases on Solids
- Adsorption Isotherms (Freundlich and Langmuir Adsorption Isotherm)
- Applications of Adsorption
- Catalysis
- Adsorption Theory of Heterogeneous Catalysis
- Colloids
Chemical Equilibrium
- Introduction of Chemical Equilibrium
- Equilibrium in Physical Processes
- Equilibrium in Chemical Processes - Dynamic Equilibrium
- Law of Mass Action and Equilibrium Constant
- Homogeneous and Heterogenous Equilibria
- Characteristics of Equilibrium Constant
- Applications of Equilibrium Constants
- Le Chaterlier's Principle and Factors Altering the Composition of Equilibrium
- Industrial Application
Nuclear Chemistry and Radioactivity
- Introduction: Nuclear Chemistry is a Branch of Physical Chemistry
- Classification of Nuclides
- Nuclear Stability
- Radioactivity
- Radioactive Decays
- Modes of Decay
- Nuclear Reactions
- Applications of Radio Isotopes
Basic Principles of Organic Chemistry
- Organic Chemistry
- Structural Representation of Organic Molecules
- Classification of Organic Compounds
- Nomenclature
- Isomerism
- Theoretical Basis of Organic Reactions
Hydrocarbons
Chemistry in Everyday Life
- Chemistry in Everyday Life
- Basics of Food Chemistry
- Compounds with Medicinal Properties
- Cleansing Agents
Estimated time: 5 minutes
Maharashtra State Board: Class 12
Key Points: Resonance
Resonance occurs when a single Lewis structure cannot adequately represent the actual structure of a molecule — multiple valid Lewis structures (called canonical forms) can be drawn.
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The actual molecule does not switch between these structures; it is a resonance hybrid — a weighted average of all canonical forms.
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The energy of the resonance hybrid is always lower than the energy of any single canonical form (this energy difference is called resonance energy or resonance stabilisation energy).
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All canonical forms must have: same positions of atoms, same number of paired and unpaired electrons, similar energy.
Classic examples:
- CO₃²⁻ (carbonate ion): 3 equivalent resonance structures — each C − O bond is neither single nor double, but intermediate (~1.33 bond order)
- Ozone (O₃): 2 resonance structures with bond length ~128 pm (intermediate between O − O single bond ~148 pm and O = O double bond ~121 pm)
