Resonance Chemistry Chemical Bonding
Contents [hide]
- 1 CHEMICAL BONDING - Resonance Chemistry Notes
- 2 1. Types of Chemical Bonds
- 3 2. Octet Rule & Its Limitations
- 4 3. Valence Bond Theory (VBT) & Hybridization
- 5 4. Molecular Orbital Theory (MOT)
- 6 5. Dipole Moment (μ) and Bond Polarity
- 7 6. Resonance & Formal Charge
- 8 Tips for JEE/NEET/GATE
- 9 Resonance Chemistry Chemical Bonding
- 10 (968)-chemistry-gyan-sutra-jee-main.pdf
- 11 CHEMiCAL BOnDinG AnD MOLECULAR StRUCtURE
CHEMICAL BONDING - Resonance Chemistry Notes
Chemical bonding is one of the most important topics in Physical Chemistry for JEE, NEET, and GATE. It explains how atoms combine to form molecules through various types of forces.
1. Types of Chemical Bonds
| Bond Type | How It Forms? | Example |
|---|---|---|
| Ionic Bond | Transfer of electrons | NaCl, KCl, MgO |
| Covalent Bond | Sharing of electrons | H₂, O₂, CH₄ |
| Coordinate Bond | One atom donates a lone pair | NH₃ → BF₃, H₃O⁺ |
| Metallic Bond | Delocalized electron cloud | Cu, Fe, Ag |
| Hydrogen Bond | H atom bonded to F, O, N | H₂O, NH₃, HF |
2. Octet Rule & Its Limitations
Octet Rule → Atoms tend to gain, lose, or share electrons to complete 8 valence electrons (stable noble gas configuration).
Limitations:
Incomplete Octet: BeCl₂, BCl₃
Expanded Octet: SF₆, PCl₅
Odd Electron Species: NO, NO₂
3. Valence Bond Theory (VBT) & Hybridization
VBT: Explains bonding in terms of atomic orbitals overlapping to form bonds.
Hybridization: Mixing of orbitals to form new hybrid orbitals of equal energy.
| Hybridization | Shape | Example |
|---|---|---|
| sp | Linear (180°) | BeCl₂, CO₂ |
| sp² | Trigonal Planar (120°) | BF₃, SO₃ |
| sp³ | Tetrahedral (109.5°) | CH₄, NH₃, H₂O |
| sp³d | Trigonal Bipyramidal (90°, 120°) | PCl₅ |
| sp³d² | Octahedral (90°) | SF₆, [Ni(CN)₄]²⁻ |
4. Molecular Orbital Theory (MOT)
Atomic orbitals combine to form Molecular Orbitals (MO).
Bond Order = (Bonding e⁻ - Antibonding e⁻) / 2
Higher bond order → Stronger bond & shorter bond length.
MOT Order for O₂, F₂, etc.:
σ(1s) < σ*(1s) < σ(2s) < σ*(2s) < π(2px) = π(2py) < σ(2pz) < π(2px) = π(2py)** < σ*(2pz)
Paramagnetic molecules: O₂, B₂ (Unpaired e⁻)
Diamagnetic molecules: N₂, F₂ (All paired e⁻)
5. Dipole Moment (μ) and Bond Polarity
μ = Charge (q) × Bond Length (d)
Polar molecules: H₂O, NH₃, HF (μ ≠ 0)
Nonpolar molecules: CO₂, BF₃, CH₄ (μ = 0)
6. Resonance & Formal Charge
Resonance: Delocalization of π-electrons, stabilizing the molecule.
Example:
Ozone (O₃)
Benzene (C₆H₆)
Carbonate ion (CO₃²⁻)
Formal Charge = (Valence e⁻ - Nonbonding e⁻ - Bonding e⁻/2)
Used to determine the most stable resonance structure.
Tips for JEE/NEET/GATE
Remember hybridization rules (sp, sp², sp³)
MOT diagrams are important for O₂, N₂, F₂
Practice bond order and dipole moment questions
Know the exceptions of the octet rule
Do you need solved examples or short tricks for Chemical Bonding?
