Chapter 4: Chemical Bonding and Molecular Structure

Similar bonds in a molecule do not have the same bond enthalpies. Mainly the term average bond enthalpy is used in polyatomic molecules. It is obtained by dividing bond dissociation enthalpy by the number of bonds broken. The bond enthalpy of the OH bond is different in ethanol and water because of the difference in the electronegativity of hydrogen and carbon. As electronegativity differs in hydrogen and oxygen is higher than that in carbon and oxygen, so the O-H bond in water has more bond enthalpy than in ethanol.

Important Topics of Class 11 Chemistry Chapter 4 Chemical Bonding and Molecular Structure

1. Octet Rule
   1. Covalent Bond
   2. Lewis Representation of Simple Molecules (The Lewis Structures)
   3. Formal Charge
   4. Limitations of the Octet Rule
2. Ionic or Electrovalent Bond
   1. Lattice Enthalpy
3. Bond Parameters
   1. Bond Length
   2. Bond Angle
   3. Bond Enthalpy
   4. Bond Order
   5. Resonance Structures
   6. Polarity of Bonds
4. The Valence Shell Electron Pair Repulsion (VSEPR) Theory
5. Valence Bond Theory
   1. Orbital Overlap Concept
   2. Directional Properties of Bonds
   3. Overlapping of Atomic Orbitals
   4. Types of Overlapping and Nature of Covalent Bonds
   5. The Strength of Sigma and Pi Bonds
6. Hybridisation
   1. Types of Hybridisation
   2. Other Examples of Sp3, Sp2 and Sp Hybridisation
   3. The Hybridisation of Elements Involving D Orbitals
7. Molecular Orbital Theory
   1. Formation of Molecular Orbitals Linear Combination of Atomic Orbitals (LCAO)
   2. Conditions for the Combination Of Atomic Orbitals
   3. Types of Molecular Orbitals
   4. Energy Level Diagram for Molecular Orbitals
   5. Electronic Configuration and Molecular Behaviour
8. Bonding in Some Homonuclear Diatomic Molecules
9. Hydrogen Bonding
   1. Cause of Formation of Hydrogen Bond
   2. Types of H-bonds.