Concept: Determining Hybridization

Hybridization is the concept of mixing atomic orbitals to form new hybrid orbitals suitable for the geometry of covalent bonds. To find the hybridization of the central atom, we use the formula:

$H=\frac{1}{2}[V+M-C+A]$

Where:

• V = Number of valence electrons of the central atom
• M = Number of monovalent atoms (like H, Cl, F) bonded to the central atom
• C = Cationic charge (if any)
• A = Anionic charge (if any)

The value of H corresponds to the hybridization:

• H=2 → sp
• H=3 → sp²
• H=4 → sp³

Step-by-Step Solution:

Step 1: Find Hybridization for NO₃⁻ (Nitrate Ion)

Central atom: Nitrogen (N). Valence electrons (V) = 5.

Structure: N is bonded to 3 O atoms. One bond is a double bond, but for hybridization count, we treat all bonds as single bonds. Monovalent atoms (M) = 0 (O is not monovalent).

Anionic charge (A) = 1.

Calculation: $H=\frac{1}{2}[5+0-0+1]=\frac{1}{2}\left[6\right]=3$

H = 3 corresponds to sp² hybridization.

Step 2: Find Hybridization for NO₂⁺ (Nitronium Ion)

Central atom: Nitrogen (N). Valence electrons (V) = 5.

Structure: N is bonded to 2 O atoms. Monovalent atoms (M) = 0.

Cationic charge (C) = 1.

Calculation: $H=\frac{1}{2}[5+0-1+0]=\frac{1}{2}\left[4\right]=2$

H = 2 corresponds to sp hybridization.

Step 3: Find Hybridization for NH₄⁺ (Ammonium Ion)

Central atom: Nitrogen (N). Valence electrons (V) = 5.

Structure: N is bonded to 4 H atoms. Monovalent atoms (M) = 4.

Cationic charge (C) = 1.

Calculation: $H=\frac{1}{2}[5+4-1+0]=\frac{1}{2}\left[8\right]=4$

H = 4 corresponds to sp³ hybridization.

Final Answer:

The hybridisation of orbitals of N atom in NO₃^–, NO₂⁺ and NH₄⁺ are sp², sp, sp³ respectively.

Therefore, the correct option is: sp², sp, sp³

Related Topics

• Valence Shell Electron Pair Repulsion (VSEPR) Theory
• Molecular Geometry
• Formal Charge
• Resonance Structures

Important Formulae and Theory

Hybridization Formula:

$H=\frac{1}{2}[V+M-C+A]$

Steric Number: Another way to determine hybridization is by calculating the steric number, which is the sum of the number of atoms bonded to the central atom and the number of lone pairs on it.

• Steric Number 2 → sp hybridization (Linear geometry)
• Steric Number 3 → sp² hybridization (Trigonal planar geometry)
• Steric Number 4 → sp³ hybridization (Tetrahedral geometry)

Key Theory: Hybridization explains the observed shapes of molecules by proposing that the valence atomic orbitals of the central atom mix to form new, degenerate (same energy) hybrid orbitals. These hybrid orbitals have defined directional properties that align with the molecular geometry predicted by VSEPR theory.