Chemical Bonding

Why Do Atoms Bond?

Atoms bond to achieve stability by attaining a completely filled outer shell (octet or duplet configuration). This makes them energetically more stable.

Types of Chemical Bonds

• Ionic Bond: Formed by the transfer of electrons from a metal to a non-metal. Example: NaCl.
• Covalent Bond: Formed by the sharing of electrons between non-metals. Example: H₂O, O₂.
• Coordinate (Dative) Bond: A type of covalent bond where both shared electrons come from one atom. Example: NH₄⁺.
• Metallic Bond: Bond formed by the attraction between positively charged metal ions and the sea of delocalized electrons. Example: Fe, Cu.

Important Concepts in Bonding

• Octet Rule: Atoms try to have 8 electrons in their outermost shell.
• Duet Rule: For small atoms like H and He, stability is achieved with 2 electrons.
• Lewis Dot Structure: Diagrams that show bonding using dots for valence electrons.

Properties of Compounds

• Ionic Compounds: High melting & boiling points, conduct electricity in molten/solution state, soluble in water.
• Covalent Compounds: Low melting & boiling points, poor conductors, often insoluble in water.

Examples of Chemical Bonds

• Sodium Chloride (NaCl): Na loses 1 electron, Cl gains 1 → ionic bond.
• Water (H₂O): Each H shares 1 electron with O → covalent bond.
• Ammonium ion (NH₄⁺): Nitrogen donates a lone pair to H⁺ → coordinate bond.

Previous Year Questions

• SSC CGL 2020: What type of bond is formed in NaCl?
• Ionic Bond
• HSSC JE 2021: Covalent bonds are generally formed between?
• Non-metals
• RRB JE 2019: Which compound contains a coordinate bond?
• NH₄⁺

Conclusion

Chemical bonding is the foundation of chemistry. Understanding how atoms bond helps us predict the properties and behavior of different compounds, essential in both theoretical and applied sciences.