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 given compounds is a hypovalent compound, we need to analyze each option based on the number of valence electrons they have after bonding. A hypovalent compound is defined as one that contains less than 8 electrons in its valence shell after bonding.

### Step-by-Step Solution:

1. **Understanding Valence Electrons**:
- Valence electrons are the electrons in the outermost shell of an atom that are involved in bonding.
- Hypovalent compounds have fewer than 8 electrons around the central atom after bonding.

2. **Analyzing NF3**:
- Nitrogen (N) has 5 valence electrons.
- In NF3, nitrogen forms 3 bonds with fluorine (F), using 6 electrons (3 bond pairs).
- Nitrogen also has 2 lone pair electrons.
- Total for nitrogen = 6 (bonding) + 2 (lone pair) = 8 electrons.
- **Conclusion**: NF3 is not hypovalent.

3. **Analyzing NH3**:
- Nitrogen (N) again has 5 valence electrons.
- In NH3, nitrogen forms 3 bonds with hydrogen (H), using 6 electrons (3 bond pairs).
- Nitrogen has 1 lone pair electron.
- Total for nitrogen = 6 (bonding) + 2 (lone pair) = 8 electrons.
- **Conclusion**: NH3 is not hypovalent.

4. **Analyzing BF3**:
- Boron (B) has 3 valence electrons.
- In BF3, boron forms 3 bonds with fluorine, using 6 electrons (3 bond pairs).
- Boron has no lone pairs.
- Total for boron = 6 (bonding) + 0 (lone pair) = 6 electrons.
- **Conclusion**: BF3 is hypovalent because it has less than 8 electrons.

5. **Analyzing IF7**:
- Iodine (I) has 7 valence electrons.
- In IF7, iodine forms 7 bonds with fluorine, using 14 electrons (7 bond pairs).
- Total for iodine = 14 (bonding) + 0 (lone pair) = 14 electrons.
- **Conclusion**: IF7 is hypervalent because it has more than 8 electrons.

### Final Answer:
The hypovalent compound among the options is **BF3**.

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