The geometrical configuration (structure) of `BF_3 and NF_3` molecule is :

Options

A. The same because of same covalency of the central atom
B. Difference because `BF_3` is polar and `NF_3` is non-polar
C. Different because `BF_3` is non-polar and `NF_3` is polar
D. none of these

Answer

To determine the geometrical configuration (structure) of the molecules BF₃ (Boron Trifluoride) and NF₃ (Nitrogen Trifluoride), we can follow these steps:

### Step 1: Determine the Valence Electrons
- **BF₃**: Boron (B) has 3 valence electrons, and each Fluorine (F) has 1 valence electron. Therefore, total valence electrons = 3 + (3 × 1) = 6.
- **NF₃**: Nitrogen (N) has 5 valence electrons, and each Fluorine (F) has 1 valence electron. Therefore, total valence electrons = 5 + (3 × 1) = 8.

### Step 2: Identify Bonding Pairs and Lone Pairs
- **BF₃**: Boron forms 3 bonds with 3 Fluorine atoms. There are no lone pairs on Boron. Thus, there are 3 bonding pairs and 0 lone pairs.
- **NF₃**: Nitrogen forms 3 bonds with 3 Fluorine atoms, but it has 1 lone pair of electrons. Thus, there are 3 bonding pairs and 1 lone pair.

### Step 3: Calculate Steric Number
- **BF₃**: Steric number = Number of bonding pairs + Number of lone pairs = 3 + 0 = 3.
- **NF₃**: Steric number = Number of bonding pairs + Number of lone pairs = 3 + 1 = 4.

### Step 4: Determine Hybridization
- **BF₃**: With a steric number of 3, the hybridization is sp².
- **NF₃**: With a steric number of 4, the hybridization is sp³.

### Step 5: Determine the Molecular Geometry
- **BF₃**: The molecular geometry is trigonal planar due to the sp² hybridization.
- **NF₃**: The molecular geometry is tetrahedral due to the sp³ hybridization, but the presence of the lone pair gives it a trigonal pyramidal shape.

### Step 6: Analyze Polarity
- **BF₃**: The molecule is non-polar because the dipole moments of the B-F bonds cancel out due to its symmetrical trigonal planar shape.
- **NF₃**: The molecule is polar because the lone pair creates an asymmetry, and the dipole moments do not cancel out.

### Conclusion
- **BF₃** has a trigonal planar structure and is non-polar.
- **NF₃** has a trigonal pyramidal structure and is polar.