Cheat sheet · Class 11 · CBSE · Science Chemistry
Chemical Bonding and Molecular Structure cheat sheet
The whole chapter on one page: key formulas, facts and the points to remember, for quick revision before a test.
CBSE Class 11 · Chemistry
Cheat sheet
Chapter 4Chemical Bonding and Molecular Structure
VSEPR: lone pair–lone pair > lone pair–bond pair > bond pair–bond pair repulsion.
1. Bond Types
- Ionic: transfer of electrons (NaCl); favoured by low IE, high electron gain, high lattice enthalpy.
- Covalent: sharing (Lewis octet).
- Coordinate: both electrons from one atom.
Formal charge = V − L − ½B.
2. VSEPR Shapes
| Pairs (bp + lp) | Shape | Example |
|---|---|---|
| 2 + 0 | linear | BeCl₂, CO₂ |
| 3 + 0 | trigonal planar | BF₃ |
| 4 + 0 | tetrahedral (109.5°) | CH₄ |
| 3 + 1 | trigonal pyramidal (107°) | NH₃ |
| 2 + 2 | bent (104.5°) | H₂O |
| 5 + 0 | trigonal bipyramidal | PCl₅ |
| 6 + 0 | octahedral | SF₆ |
3. Hybridisation
| Type | Geometry |
|---|---|
| sp | linear 180° |
| sp² | trigonal 120° |
| sp³ | tetrahedral 109.5° |
| sp³d | trigonal bipyramidal |
| sp³d² | octahedral |
4. MO Theory
- Higher bond order ⇒ shorter, stronger bond.
- O₂ is paramagnetic (2 unpaired electrons), bond order 2.
- N₂: bond order 3.
5. Polarity & H-bonding
- Dipole moment (debye).
- CO₂, BF₃, CH₄: μ = 0 (symmetry).
- H-bond: H attached to F, O or N; explains high b.p. of water.
6. Key Points
- σ bonds form by head-on overlap; π by sideways.
- Fajans: small cation, large anion ⇒ more covalent.
- Resonance stabilises (O₃, CO₃²⁻).
- Bond length ∝ 1/bond order.
Remember: VSEPR table | hybridisation | bond order = ½(N_b − N_a)
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