Chemical Bonding Class 11 Notes
Ionic, covalent, metallic bonds, VSEPR theory, hybridisation, MO theory, and hydrogen bonding.
Chemical Bonding — Detailed Notes
Chemical Bonding is an important chapter in Chemistry and is frequently tested in both conceptual and application-based questions. Students should first understand the core definition, then connect the topic with real-life observations and exam patterns.
Chemical bonding is the force of attraction that holds atoms together in a molecule or compound, arising from redistribution of electrons. In school and entrance exams, questions usually check your conceptual clarity, step-wise logic, and ability to avoid common mistakes.
To prepare effectively, break Chemical Bonding into smaller sub-parts: definition, laws/rules, examples, formulas, and revision questions. After theory, solve short questions, then move to mixed-level numericals or application prompts.
A smart revision strategy is to maintain a one-page summary for Chemical Bonding. Include important terms, two solved examples, and last-minute checkpoints before exams.
Key Exam Points
- Ionic bond: complete electron transfer from metal to non-metal (e.g., NaCl). High mp/bp, conducts when molten/dissolved.
- Covalent bond: electron sharing between non-metals (e.g., H₂O, CO₂). Can be polar or non-polar.
- VSEPR theory: electron pairs repel — lone pair > bond pair; determines molecular geometry.
- Hybridisation: sp (linear, 180°), sp² (trigonal planar, 120°), sp³ (tetrahedral, 109.5°).
- Hydrogen bond: weak electrostatic attraction between H (bonded to N/O/F) and electronegative atom.
- Fajan's rules: higher charge density → more covalent character in ionic compounds.
Important Formula / Rule
Bond order = (Bonding electrons - Antibonding electrons) / 2. VSEPR: AXₙEₘ (A=central, X=bond, E=lone pair).
What You Will Learn in Chemical Bonding
Chemical bonding is the force of attraction that holds atoms together in a molecule or compound, arising from redistribution of electrons.
- Ionic bond: complete electron transfer from metal to non-metal (e.g., NaCl). High mp/bp, conducts when molten/dissolved.
- Covalent bond: electron sharing between non-metals (e.g., H₂O, CO₂). Can be polar or non-polar.
- VSEPR theory: electron pairs repel — lone pair > bond pair; determines molecular geometry.
- Hybridisation: sp (linear, 180°), sp² (trigonal planar, 120°), sp³ (tetrahedral, 109.5°).
- Hydrogen bond: weak electrostatic attraction between H (bonded to N/O/F) and electronegative atom.
- Fajan's rules: higher charge density → more covalent character in ionic compounds.
Key Formula
Bond order = (Bonding electrons - Antibonding electrons) / 2. VSEPR: AXₙEₘ (A=central, X=bond, E=lone pair).
Example
Water (H₂O) has sp³ hybridisation with 2 lone pairs giving a bent shape (104.5°).
Solved Numerical Example
Calculate bond order of O₂ using MO theory. Molecular orbital config of O₂: σ1s² σ*1s² σ2s² σ*2s² σ2p² π2p⁴ π*2p². Bonding e⁻ = 8, Antibonding e⁻ = 4. Bond order = (8-4)/2 = 2. O₂ has a double bond and 2 unpaired electrons (paramagnetic).
Expected Exam Questions — Chemical Bonding
Q1.Explain the VSEPR theory. Predict the shape of NH₃ and H₂O.
Q2.Why is the boiling point of H₂O much higher than H₂S?
Q3.What is the hybridisation of carbon in CH₄, C₂H₄, and C₂H₂?
🔘 MCQ Practice — Chemical Bonding
MCQ 1.Which of the following has a tetrahedral geometry?
✓ Correct Answer: CH₄
MCQ 2.The type of bond present in NaCl is:
✓ Correct Answer: Ionic
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