How many nitrogen is/are `sp^(2)`. Hybridised in hydrazoic acid?

Answer

To determine how many nitrogen atoms are `sp^2` hybridized in hydrazoic acid (HN₃), we will follow these steps:

### Step 1: Understand the Structure of Hydrazoic Acid
Hydrazoic acid has the formula HN₃. The structure can be represented as H-N=N≡N. In this structure, there are three nitrogen atoms connected to one hydrogen atom.

### Step 2: Identify the Hybridization of Each Nitrogen Atom
To find the hybridization of each nitrogen atom, we need to calculate the steric number (SN) for each nitrogen atom. The steric number can be calculated using the formula:
\[ \text{Steric Number (SN)} = \frac{1}{2} \left( \text{Number of valence electrons} + \text{Number of attached atoms} - \text{Cationic charge} + \text{Anionic charge} \right) \]

### Step 3: Calculate Steric Number for Each Nitrogen Atom

#### For Nitrogen 1 (the one bonded to hydrogen):
- Valence electrons = 5 (for nitrogen)
- Attached atoms = 1 (the hydrogen)
- Cationic charge = 0
- Anionic charge = 0

Calculating SN:
\[ \text{SN} = \frac{1}{2} (5 + 1 - 0 + 0) = \frac{1}{2} (6) = 3 \]
Since SN = 3, the hybridization is `sp^2`.

#### For Nitrogen 2 (the one in the double bond):
- Valence electrons = 5
- Attached atoms = 0 (it is bonded to another nitrogen)
- Cationic charge = 1 (due to the positive charge on nitrogen 1)
- Anionic charge = 0

Calculating SN:
\[ \text{SN} = \frac{1}{2} (5 + 0 - 1 + 0) = \frac{1}{2} (4) = 2 \]
Since SN = 2, the hybridization is `sp`.

#### For Nitrogen 3 (the terminal nitrogen):
- Valence electrons = 5
- Attached atoms = 0 (it is bonded to another nitrogen)
- Cationic charge = 0
- Anionic charge = 1 (due to the negative charge on nitrogen 3)

Calculating SN:
\[ \text{SN} = \frac{1}{2} (5 + 0 - 0 + 1) = \frac{1}{2} (6) = 3 \]
Since SN = 3, the hybridization is `sp^2`.

### Step 4: Conclusion
In hydrazoic acid (HN₃), there are **two nitrogen atoms** that are `sp^2` hybridized (Nitrogen 1 and Nitrogen 3).

### Summary
- Nitrogen 1: `sp^2` hybridized
- Nitrogen 2: `sp` hybridized
- Nitrogen 3: `sp^2` hybridized

Thus, the answer is that there are **2 nitrogen atoms that are `sp^2` hybridized** in hydrazoic acid.

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