How may possible `angle FSeF` bond angles are present in `SeF_(4)` molecule ?

Answer

To determine the possible bond angles between the fluorine atoms in the SeF₄ molecule, we can follow these steps:

### Step 1: Determine the Valence Electrons of Selenium
Selenium (Se) is in Group 16 of the periodic table and has 6 valence electrons.

### Step 2: Identify the Bonds Formed
In SeF₄, selenium forms four covalent bonds with four fluorine (F) atoms. This uses 4 of its 6 valence electrons, leaving 2 electrons as a lone pair.

### Step 3: Calculate the Steric Number
The steric number is calculated as the number of bonded atoms plus the number of lone pairs. Here, we have:
- 4 bond pairs (from 4 F atoms)
- 1 lone pair

Thus, the steric number is 4 + 1 = 5.

### Step 4: Determine the Hybridization
With a steric number of 5, the hybridization of Se in SeF₄ is sp³d.

### Step 5: Identify the Molecular Geometry
The molecular geometry for a molecule with a steric number of 5 and one lone pair is seesaw. The lone pair occupies an equatorial position in the trigonal bipyramidal arrangement.

### Step 6: Analyze the Bond Angles
In a seesaw geometry, the bond angles between the fluorine atoms can be analyzed:
- The angle between two equatorial fluorine atoms (F-Se-F) is approximately 120 degrees.
- The angle between an equatorial fluorine and an axial fluorine is approximately 90 degrees.
- The angle between two axial fluorine atoms is 180 degrees.

### Step 7: Count the Unique Bond Angles
The unique bond angles between the F atoms in SeF₄ are:
1. 90 degrees (between equatorial and axial F)
2. 120 degrees (between equatorial F)
3. 180 degrees (between axial F)

### Conclusion
Thus, there are a total of **6 unique F-Se-F bond angles** in the SeF₄ molecule.

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