Introduction to Ionic Bonding

Introduction

Cations and anions are formed in such a way that the "Octet Rule" is satisfied.

Example:

Na(s) + ½Cl₂ → NaCl(s)
ΔH°_r = − 410.9 Kj (highly exothermic) Both Na and Cl in NaCl have inert gas configuration.
ionic-bonding

Energetics of Ionic Bond Formation

Definition: Lattice energy is the energy required to completely separate an ionic solid into its gaseous ions. E₁ = κ(Q₁Q₂)/d
Where: κ is a constant = 8.99 x 10⁹ J·m/C², Q₁ and Q₂ are the charges on the ions, d is the distance between ions.

Lattice energy depends on:

Charges on the ions (Q₁ and Q₂)
Sizes of the ions (d)

Lattice energy increases as:

Charges on the ions increase
The distance between the ions decreases

Exercise: Energetics of Ionic Bond Formation

Exercise: Energetics of Ionic Bond Formation

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Solutions

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