How many resonance structures can be drawn for the nitrate ion, `NO_3^(-)`?

Options

A. 1
B. 2
C. 3
D. 4

Explanation

To determine how many resonance structures can be drawn for the nitrate ion, \( \text{NO}_3^{-} \), we can follow these steps:

### Step 1: Determine the Valence Electrons
First, we need to calculate the total number of valence electrons available for the nitrate ion.

- Nitrogen (N) has 5 valence electrons.
- Each oxygen (O) has 6 valence electrons, and there are three oxygen atoms.
- The nitrate ion has an overall charge of -1, which means we need to add one extra electron.

Total valence electrons = \( 5 + (3 \times 6) + 1 = 24 \) electrons.

### Step 2: Draw the Lewis Structure
Next, we will draw the Lewis structure for the nitrate ion.

- Place nitrogen in the center and connect it to the three oxygen atoms.
- To satisfy the octet rule, we can form one double bond between nitrogen and one oxygen atom, and single bonds with the other two oxygen atoms.
- The oxygen atoms that are single-bonded will each carry a negative charge.

### Step 3: Identify Resonance Structures
Now, we need to identify the resonance structures.

- The double bond can be between nitrogen and any one of the three oxygen atoms.
- Therefore, we can have three different resonance structures by moving the double bond among the three oxygen atoms.

### Step 4: Draw the Resonance Structures
1. **First Resonance Structure**: Nitrogen double-bonded to the first oxygen, with the other two oxygens each carrying a negative charge.
2. **Second Resonance Structure**: Nitrogen double-bonded to the second oxygen, with the other two oxygens each carrying a negative charge.
3. **Third Resonance Structure**: Nitrogen double-bonded to the third oxygen, with the other two oxygens each carrying a negative charge.

### Conclusion
Thus, the nitrate ion \( \text{NO}_3^{-} \) has a total of **three resonance structures**.

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