Number of sigma and pi bonds in `ClO_(2)^(-)` ion

Options

A. `4 sigma and 4pi`
B. `4 sigma and 2pi`
C. `4 sigma and 3pi`
D. `3 sigma and 2pi`

Answer

To determine the number of sigma (σ) and pi (π) bonds in the ClO₂⁻ ion, we can follow these steps:

### Step 1: Determine the Lewis Structure
- The first step is to draw the Lewis structure of the ClO₂⁻ ion. Chlorine (Cl) is the central atom, and it is bonded to two oxygen (O) atoms. The negative charge indicates that there is an extra electron.

### Step 2: Count the Valence Electrons
- Chlorine has 7 valence electrons, and each oxygen has 6 valence electrons. Since there are two oxygen atoms, we have:
- Chlorine: 7 electrons
- Oxygen: 2 × 6 = 12 electrons
- Additional electron due to the negative charge: +1 electron
- Total = 7 + 12 + 1 = 20 valence electrons.

### Step 3: Distribute Electrons
- Place Cl in the center and connect it to the two O atoms with single bonds. This uses 4 electrons (2 for each bond).
- We have 20 - 4 = 16 electrons remaining.
- Distribute the remaining electrons to satisfy the octet rule for the oxygen atoms. Each oxygen will receive 6 electrons (3 lone pairs) to complete their octet.

### Step 4: Form Double Bonds
- Since chlorine can expand its octet, we can form a double bond between Cl and one of the O atoms. This will use 2 electrons from the lone pairs of one oxygen atom and will create a double bond (1 σ bond and 1 π bond).
- The structure will now have:
- One Cl=O double bond (1 σ + 1 π)
- One Cl-O single bond (1 σ)

### Step 5: Count the Bonds
- Now we can count the number of sigma and pi bonds:
- From the Cl=O double bond: 1 σ bond and 1 π bond.
- From the Cl-O single bond: 1 σ bond.
- Total:
- Sigma (σ) bonds = 2 (1 from the double bond + 1 from the single bond)
- Pi (π) bonds = 1 (from the double bond)

### Final Answer
- The ClO₂⁻ ion has **2 sigma bonds** and **1 pi bond**.

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