Mode:
Active Reaction Ready
Subatomic Reaction Chamber
ΔEN = 2.23 (70% Ionic Character)
Sodium (Na) + Chlorine (Cl) → IONIC BOND
Na
Z = 11
Sodium
[Ne] 3s¹ (1 valence e⁻)
e⁻
Exothermic Transfer →
Cl
Z = 17
Chlorine
[Ne] 3s² 3p⁵ (7 valence e⁻)
Pauling Electronegativity Difference
Reactant A Electronegativity:
0.93
Reactant B Electronegativity:
3.16
Absolute Difference (|ΔEN|):
2.23
According to Pauling's equation: % Ionic Character = 100 × (1 - e^(-(ΔEN/2)²)). When ΔEN exceeds 1.7, the bond is classified as predominantly ionic.
Lewis Structure & Octet Rule
[Na]⁺ [ :Cl: ]⁻
✓ Both ions achieve inert Noble Gas electronic octets ([Ne] and [Ar])
Sodium donates its lone 3s valence electron to become Na⁺ ([Ne]), while Chlorine accepts it to complete its 3p valence subshell as Cl⁻ ([Ar]).
VSEPR Geometry & Lattice Energy
Predicted Geometry:
Face-Centered Cubic (FCC Lattice)
Lattice Enthalpy (ΔH_lattice):
~ -787 kJ/mol
Dipole Moment (μ):
9.0 Debye (Extreme)
High lattice enthalpy stabilizes the 3D ionic crystal network, imparting high melting points (801 °C) and brittle mechanical cleavage planes.
Fajan's Rules for Partial Covalent Character in Ionic Bonds
Class 11 NCERT
1. Cation Size: Smaller cations have higher charge density and stronger polarizing power (e.g. LiCl is more covalent than KCl).
2. Anion Size: Larger anions have more diffuse electron clouds, making them more easily polarized by the cation (e.g. AgI > AgCl in covalency).
3. Pseudo-Noble Gas Configuration: Cations with 18 electrons in outer shell (ns² np⁶ nd¹⁰, e.g. Cu⁺) have greater polarizing power than inert gas configurations (ns² np⁶, e.g. Na⁺).