Which of the following species is neither hypervalent nor hypovalent ?

Options

A. `ClO_(4)^(-)`
B. `BF_(3)`
C. `SO_(4)^(2-)`
D. `CO_(3)^(2-)`

Explanation

To determine which of the following species is neither hypervalent nor hypovalent, we need to analyze each species based on the definition of hypervalent and hypovalent compounds.

**Definitions:**
1. **Hypervalent Compounds**: Compounds in which the central atom has more than 8 electrons in its valence shell.
2. **Hypovalent Compounds**: Compounds in which the central atom has less than 8 electrons in its valence shell.

**Step-by-Step Solution:**

1. **Identify the Species**: We have four species to analyze: ClO₄⁻, BF₃, SO₄²⁻, and CO₃²⁻.

2. **Analyze ClO₄⁻**:
- Chlorine (Cl) has 7 valence electrons.
- In ClO₄⁻, Cl forms double bonds with three O atoms and a single bond with one O atom that carries a negative charge.
- Total valence electrons around Cl = 14 (7 from Cl + 7 from 3 O + 1 from the negatively charged O).
- Since Cl has more than 8 electrons, ClO₄⁻ is **hypervalent**.

3. **Analyze BF₃**:
- Boron (B) has 3 valence electrons.
- In BF₃, B forms single bonds with three F atoms.
- Total valence electrons around B = 6 (3 from B + 3 from F).
- Since B has less than 8 electrons, BF₃ is **hypovalent**.

4. **Analyze SO₄²⁻**:
- Sulfur (S) has 6 valence electrons.
- In SO₄²⁻, S forms two double bonds with two O atoms and two single bonds with two O atoms that carry negative charges.
- Total valence electrons around S = 12 (6 from S + 6 from 2 double-bonded O + 2 from 2 negatively charged O).
- Since S has more than 8 electrons, SO₄²⁻ is **hypervalent**.

5. **Analyze CO₃²⁻**:
- Carbon (C) has 4 valence electrons.
- In CO₃²⁻, C forms one double bond with one O atom and two single bonds with two O atoms that carry negative charges.
- Total valence electrons around C = 8 (4 from C + 4 from 2 single-bonded O + 4 from double-bonded O).
- Since C has exactly 8 electrons, CO₃²⁻ is **neither hypervalent nor hypovalent**.

**Conclusion**: The species that is neither hypervalent nor hypovalent is **CO₃²⁻**.

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