Which of the following species has the largest bond angle?

Options

A. `NH_(4)^(+)`
B. `NO_(2)^(+)`
C. `NO_(2)^(-)`
D. `NO_(3)^(-)`

Explanation

To determine which of the given species has the largest bond angle, we will analyze each option step by step.

### Step 1: Analyze Ammonium (NH4+)
- **Structure**: Ammonium has a tetrahedral structure with nitrogen at the center and four hydrogen atoms at the corners.
- **Hybridization**: The hybridization of nitrogen in NH4+ is sp³.
- **Bond Angle**: The bond angle in a tetrahedral structure is approximately 109.5°.

### Step 2: Analyze Nitronium Ion (NO2+)
- **Structure**: The nitronium ion has nitrogen bonded to two oxygen atoms with a positive charge on nitrogen.
- **Hybridization**: The hybridization of nitrogen in NO2+ is sp.
- **Bond Angle**: The bond angle in a linear structure (due to sp hybridization) is 180°.

### Step 3: Analyze Nitrogen Dioxide (NO2-)
- **Structure**: In NO2-, nitrogen is bonded to one oxygen with a double bond and another oxygen with a single bond, where the latter has three lone pairs.
- **Hybridization**: The hybridization of nitrogen in NO2- is sp².
- **Bond Angle**: The bond angle in a trigonal planar structure is approximately 120°.

### Step 4: Analyze Nitrate Ion (NO3-)
- **Structure**: The nitrate ion has nitrogen bonded to three oxygen atoms, with one double bond and two single bonds, and carries a negative charge.
- **Hybridization**: The hybridization of nitrogen in NO3- is also sp².
- **Bond Angle**: The bond angle in a trigonal planar structure is approximately 120°.

### Step 5: Compare Bond Angles
- **Ammonium (NH4+)**: 109.5°
- **Nitronium Ion (NO2+)**: 180°
- **Nitrogen Dioxide (NO2-)**: 120°
- **Nitrate Ion (NO3-)**: 120°

### Conclusion
The species with the largest bond angle is the nitronium ion (NO2+), which has a bond angle of 180°.

### Final Answer
**The species with the largest bond angle is NO2+ (option B).**

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