ICSE Class 10 Chemistry: Chemical Bonding — Complete Notes 2026

Why Do Atoms Bond?

• Atoms bond to achieve stable octet (noble gas configuration)
• Valence electrons determine bonding capacity; Lewis dot structures
• Types of bonds: ionic (transfer), covalent (sharing), coordinate (dative)

Ionic Bonding

• Formation: metal loses electrons, non-metal gains; electrostatic attraction
• Electron dot diagrams for NaCl, MgO, CaCl₂
• Properties: high mp/bp, soluble in water, conducts electricity when molten/dissolved

Covalent Bonding

• Single (H₂), double (O₂), triple (N₂) bonds; shared electron pairs
• Lewis dot structures: H₂O, NH₃, CO₂, CH₄, HCl
• Properties: low mp/bp, poor conductors, often soluble in organic solvents

Coordinate (Dative) Bond

• Both electrons in bond donated by one atom (donor) to electron-deficient atom (acceptor)
• Examples: NH₄⁺ (N donates to H⁺), H₃O⁺, SO₃·BF₃ adduct
• Once formed, coordinate bond is indistinguishable from covalent bond

Polar and Non-Polar Covalent Bonds

• Polarity arises from electronegativity difference between bonded atoms
• H₂O and NH₃ are polar molecules; CO₂ and CCl₄ are non-polar (symmetrical)
• Polar molecules have dipole moment; affects solubility and intermolecular forces

Metallic Bonding (Introduction)

• Sea of delocalised electrons surrounding positive metal ions (lattice)
• Explains electrical conductivity, malleability, ductility and lustre of metals
• Strength increases with more valence electrons and smaller ionic radius

ICSE Exam Tips — Bonding

• Always draw correct electron dot structures — marks allocated for each bond
• Identify bond type from electronegativity difference: >1.7 ionic, 0.4–1.7 polar covalent, <0.4 non-polar
• Common exam question: compare properties of NaCl and CCl₄