⚛️ UNIT: CHEMICAL BONDING

Introduction

Chemical bonding refers to the force of attraction that holds atoms or ions together to form molecules and compounds. The type of bond formed depends on how electrons are arranged and shared or transferred between atoms.

Types of Chemical Bonds

There are three main types of chemical bonds:

• Ionic Bond – formed by transfer of electrons between metals and non-metals.
• Covalent Bond – formed by sharing of electrons between non-metal atoms.
• Metallic Bond – formed among metal atoms through attraction between positive ions and delocalised electrons.

Ionic Bonding

Ionic bonding involves the transfer of electrons to form oppositely charged ions which attract each other.

• Occurs between metals and non-metals.
• Metals lose electrons to form cations.
• Non-metals gain electrons to form anions.

Examples: NaCl, MgCl₂, CaO

Sodium chloride forms a giant ionic lattice where each Na⁺ ion is surrounded by six Cl⁻ ions in a cubic arrangement.

Covalent Bonding

Covalent bonding occurs when non-metal atoms share electrons to achieve stable electron arrangements.

• Forms molecules instead of ions.
• Each shared pair of electrons forms one covalent bond.
• Double and triple bonds may occur.

Examples: H₂, Cl₂, NH₃, H₂O, CO₂, CH₄, N₂, O₂

Metallic Bonding

In metallic bonding, outer electrons become delocalised and move freely between metal ions, forming a strong bond.

• Explains electrical and thermal conductivity.
• Accounts for malleability and ductility of metals.

Examples: Copper (Cu), Aluminium (Al)