Which nitrogen trihalides is least basic

Options

A. `NF_(3)`
B. `NCl_(3)`
C. `NBr_(3)`
D. `NI_(3)`

Explanation

To determine which nitrogen trihalide is the least basic among NF3, NCl3, NBr3, and NI3, we need to analyze the basicity of these compounds based on the properties of the halides involved.

### Step-by-Step Solution:

1. **Understanding Basicity**: Basicity in this context refers to the ability of the nitrogen trihalides to donate a lone pair of electrons from nitrogen to accept protons (H+ ions). The more stable the nitrogen trihalide, the less basic it is, as it will be less likely to donate its lone pair.

2. **Analyzing the Halides**: The nitrogen trihalides consist of nitrogen bonded to different halogens: fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). The order of the halogens in terms of size and electronegativity is:
- F (smallest, most electronegative)
- Cl
- Br
- I (largest, least electronegative)

3. **Effect of Electronegativity**: Fluorine is the most electronegative element, which means it attracts electrons strongly. This strong attraction makes the nitrogen-fluorine bond very stable and less likely to donate its lone pair, resulting in lower basicity.

4. **Comparing Basicity**:
- **NF3**: The bond between nitrogen and fluorine is very strong and stable due to the high electronegativity of fluorine. Therefore, NF3 is the least basic.
- **NCl3**: Chlorine is less electronegative than fluorine, making NCl3 more basic than NF3.
- **NBr3**: Bromine is even less electronegative than chlorine, so NBr3 is more basic than NCl3.
- **NI3**: Iodine is the least electronegative of the halogens, making NI3 the most basic of the four.

5. **Conclusion**: Based on the analysis, the order of basicity from least to most basic is:
- NF3 < NCl3 < NBr3 < NI3

Thus, the nitrogen trihalide that is least basic is **NF3**.