Which of the following is electron deficient?

Options

A. Icl
B. `NH_(3)`
C. `BCl_(3)`
D. `PCl_(3)`

Answer

To determine which of the given species is electron deficient, we will analyze each species one by one, focusing on their valence electrons and bonding characteristics.

### Step-by-Step Solution:

1. **Identify the species**: We have four species to analyze: ICl, NH3, BCl3, and PCl3.

2. **Analyze ICl (Iodine monochloride)**:
- Iodine (I) has 7 valence electrons, and Chlorine (Cl) also has 7 valence electrons.
- In ICl, iodine forms a single bond with chlorine, using 1 of its 7 electrons.
- Iodine has 3 lone pairs remaining, and chlorine has 3 lone pairs after forming the bond.
- Total electrons around iodine: 1 (bonding) + 6 (lone pairs) = 7 electrons.
- Total electrons around chlorine: 1 (bonding) + 6 (lone pairs) = 7 electrons.
- Both atoms have complete octets (8 electrons), so ICl is **not electron deficient**.

3. **Analyze NH3 (Ammonia)**:
- Nitrogen (N) has 5 valence electrons.
- In NH3, nitrogen forms 3 bonds with hydrogen and has 1 lone pair.
- Total electrons around nitrogen: 3 (bonding) + 2 (from lone pair) = 5 electrons.
- Each hydrogen contributes 1 electron, so nitrogen effectively has 8 electrons around it.
- Therefore, NH3 is **not electron deficient**.

4. **Analyze BCl3 (Boron trichloride)**:
- Boron (B) has 3 valence electrons, and each chlorine has 7 valence electrons.
- In BCl3, boron forms 3 bonds with chlorine.
- Total electrons around boron: 3 (bonding) = 3 electrons.
- Each chlorine contributes 1 electron, leading to a total of 6 electrons around boron.
- Boron has only 6 electrons and does not complete its octet, making it **electron deficient**.

5. **Analyze PCl3 (Phosphorus trichloride)**:
- Phosphorus (P) has 5 valence electrons.
- In PCl3, phosphorus forms 3 bonds with chlorine and has 1 lone pair.
- Total electrons around phosphorus: 3 (bonding) + 2 (from lone pair) = 5 electrons.
- Each chlorine contributes 1 electron, leading to a total of 8 electrons around phosphorus.
- Therefore, PCl3 is **not electron deficient**.

6. **Conclusion**:
- The only species that is electron deficient is **BCl3**.

### Final Answer:
The electron deficient species is **BCl3**.