Which of the following is a the most preferred and hence of the lower energy for `SO_(3)`?

Options

A.
B.
C.
D.

Explanation

To determine the most preferred and lowest energy structure for sulfur trioxide (SO₃), we need to calculate the formal charges for the different resonance structures of SO₃. Here’s a step-by-step solution:

### Step 1: Identify the Valence Electrons
- Sulfur (S) has 6 valence electrons.
- Each oxygen (O) has 6 valence electrons, and there are three oxygen atoms.
- Total valence electrons = 6 (from S) + 3 × 6 (from O) = 24 valence electrons.

### Step 2: Draw the Lewis Structures
- The most common Lewis structure for SO₃ has sulfur in the center with three oxygen atoms bonded to it.
- Each S-O bond is a double bond in the most stable structure.

### Step 3: Calculate Formal Charges for the First Structure
1. **For Sulfur (S)**:
- Valence electrons = 6
- Non-bonding electrons = 0 (all are involved in bonding)
- Bonding electrons = 12 (6 bonds, each counted as 2)
- Formal charge = Valence electrons - Non-bonding electrons - (Bonding electrons / 2)
- Formal charge = 6 - 0 - (12 / 2) = 6 - 0 - 6 = 0

2. **For Each Oxygen (O)**:
- Valence electrons = 6
- Non-bonding electrons = 4 (2 lone pairs)
- Bonding electrons = 4 (2 bonds)
- Formal charge = 6 - 4 - (4 / 2) = 6 - 4 - 2 = 0

### Step 4: Calculate Formal Charges for the Second Structure
1. **For Sulfur (S)**:
- Valence electrons = 6
- Non-bonding electrons = 2 (one lone pair)
- Bonding electrons = 6 (3 single bonds)
- Formal charge = 6 - 2 - (6 / 2) = 6 - 2 - 3 = 1

2. **For Each Oxygen (O)**:
- Valence electrons = 6
- Non-bonding electrons = 6 (3 lone pairs)
- Bonding electrons = 2 (1 bond)
- Formal charge = 6 - 6 - (2 / 2) = 6 - 6 - 1 = -1

### Step 5: Compare the Formal Charges
- In the first structure, all atoms have a formal charge of 0.
- In the second structure, sulfur has a formal charge of +1 and two oxygens have a formal charge of -1.

### Conclusion
The first structure, where all atoms have a formal charge of 0, is the most preferred and has the lower energy.

### Final Answer
The most preferred and hence lower energy structure for SO₃ is the one where all formal charges are zero.

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