How many `sigma and pi` bonds are there in calcium cyanamide `Ca(CN)_2` ?

Options

A. `2sigma and 1pi`
B. `2 pi and 2 sigma`
C. `1 sigma and 2 pi`
D. `2 sigma and 3 pi`.

Answer

To determine the number of sigma (σ) and pi (π) bonds in calcium cyanamide, \( \text{Ca(CN)}_2 \), we can follow these steps:

### Step 1: Understand the Structure of Calcium Cyanamide
Calcium cyanamide consists of one calcium ion (Ca²⁺) and two cyanide ions (CN⁻). The calcium ion forms ionic bonds with the cyanide ions.

### Step 2: Analyze the Cyanide Ion
Each cyanide ion (CN⁻) has a carbon atom triple-bonded to a nitrogen atom. The bonding in the cyanide ion can be broken down as follows:
- **1 σ bond**: This is formed by the head-on overlap of the carbon and nitrogen atoms.
- **2 π bonds**: These are formed by the sidewise overlap of the remaining p orbitals on the carbon and nitrogen atoms.

### Step 3: Count the Bonds in Calcium Cyanamide
Since there are two cyanide ions in calcium cyanamide, we need to multiply the number of bonds in one cyanide ion by two:
- **Total σ bonds from both CN⁻ ions**: \( 1 \, \sigma \, \text{(from one CN)} \times 2 \, \text{(two CN)} = 2 \, \sigma \, \text{bonds} \)
- **Total π bonds from both CN⁻ ions**: \( 2 \, \pi \, \text{(from one CN)} \times 2 \, \text{(two CN)} = 4 \, \pi \, \text{bonds} \)

### Step 4: Identify the Ionic Bond
The bond between calcium and the cyanide ions is ionic, meaning it does not contribute to the count of sigma or pi bonds.

### Final Count of Bonds
- **Total σ bonds**: 2
- **Total π bonds**: 4

### Conclusion
In calcium cyanamide \( \text{Ca(CN)}_2 \), there are **2 sigma bonds** and **4 pi bonds**.

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