Which of the following is a hypovalent compound?

Options

A. `NF_3`
B. `NH_3`
C. `BF_3`
D. `IF_7`

Answer

To determine which of the following compounds is hypovalent, we need to understand the concept of hypovalent compounds. Hypovalent compounds are those in which the central atom has fewer than 8 valence electrons in its outer shell.

### Step-by-Step Solution:

1. **Define Hypovalent Compounds**:
- Hypovalent compounds are characterized by having a central atom that does not achieve an octet configuration, meaning it has fewer than 8 electrons in its valence shell.

2. **Analyze Each Compound**:
- **Nitrogen Trifluoride (NF₃)**:
- Nitrogen has 5 valence electrons.
- In NF₃, nitrogen forms three bonds with fluorine atoms, using 3 of its valence electrons.
- Total valence electrons around nitrogen: 5 (from nitrogen) + 3 (from bonds) = 8.
- Conclusion: NF₃ is not hypovalent.

- **Ammonia (NH₃)**:
- Nitrogen again has 5 valence electrons.
- In NH₃, nitrogen forms three bonds with hydrogen atoms and has one lone pair.
- Total valence electrons around nitrogen: 5 (from nitrogen) + 3 (from bonds) + 2 (from lone pair) = 10.
- Conclusion: NH₃ is not hypovalent.

- **Boron Trifluoride (BF₃)**:
- Boron has 3 valence electrons.
- In BF₃, boron forms three bonds with fluorine atoms, using all of its valence electrons.
- Total valence electrons around boron: 3 (from boron) + 6 (from bonds) = 6.
- Conclusion: BF₃ has fewer than 8 valence electrons and is therefore hypovalent.

3. **Identify the Correct Answer**:
- Among the compounds analyzed, only BF₃ has fewer than 8 valence electrons, making it the hypovalent compound.

### Final Answer:
The hypovalent compound is **Boron Trifluoride (BF₃)**.