the structure of `SF_6` is octahedral. what is the structure of `SF_4`

Options

A. Trigonal bipyramidal
B. pyramidal
C. square planar
D. trigonal planar

Answer

To determine the structure of SF₄, we can follow these steps:

### Step 1: Calculate the total valence electrons
- Sulfur (S) has 6 valence electrons.
- Each Fluorine (F) has 7 valence electrons, and there are 4 Fluorine atoms.
- Total valence electrons = Valence electrons of S + (Valence electrons of F × Number of F atoms)

\[ \text{Total valence electrons} = 6 + (7 \times 4) = 6 + 28 = 34 \]

### Step 2: Determine the number of bond pairs and lone pairs
- To find the number of bond pairs, we divide the total valence electrons by 8 and take the quotient.
- To find the number of lone pairs, we take the remainder from the division and divide it by 2.

\[ \text{Bond pairs} = \frac{34}{8} = 4 \quad (\text{quotient}) \]
\[ \text{Remainder} = 34 - (8 \times 4) = 2 \]
\[ \text{Lone pairs} = \frac{2}{2} = 1 \]

### Step 3: Identify the molecular geometry
- We have 4 bond pairs and 1 lone pair.
- The arrangement of 4 bond pairs and 1 lone pair corresponds to a trigonal bipyramidal geometry.
- The presence of a lone pair will distort this geometry, leading to a seesaw shape.

### Step 4: Draw the structure
- Place the sulfur atom in the center.
- Arrange the 4 fluorine atoms in the equatorial and axial positions, with one lone pair occupying an equatorial position.

The structure can be visualized as follows:
- 2 fluorine atoms in the equatorial plane.
- 1 fluorine atom in the axial position above the sulfur.
- 1 fluorine atom in the axial position below the sulfur.
- The lone pair occupies one of the equatorial positions.

### Conclusion
- The structure of SF₄ is a seesaw shape, which is derived from the trigonal bipyramidal geometry due to the presence of one lone pair.