Which of the following species is hypervalent?

Options

A. `ClO_4^(-)`
B. `PO_4^(3-)`
C. `SO_3^(2-)`
D. All of these

Explanation

To determine which of the following species is hypervalent, we need to follow these steps:

### Step 1: Understand the Definition of Hypervalent
A hypervalent species is defined as one where the central atom has more than 8 electrons in its valence shell. This usually occurs in elements from the third period and beyond in the periodic table, where d-orbitals can participate in bonding.

### Step 2: Analyze Each Species
We will analyze each species provided to see if the central atom exceeds 8 valence electrons.

1. **ClO4- (Chlorate ion)**:
- Chlorine (Cl) has 7 valence electrons.
- In ClO4-, chlorine is bonded to four oxygen atoms.
- Each bond with oxygen can be counted as 2 electrons (one from Cl and one from O).
- Total electrons around Cl = 4 bonds × 2 electrons/bond = 8 electrons.
- Chlorine does not exceed 8 electrons, so ClO4- is **not hypervalent**.

2. **PO4^3- (Phosphate ion)**:
- Phosphorus (P) has 5 valence electrons.
- In PO4^3-, phosphorus is bonded to four oxygen atoms.
- Total electrons around P = 4 bonds × 2 electrons/bond = 8 electrons.
- Phosphorus does not exceed 8 electrons, so PO4^3- is **not hypervalent**.

3. **SO4^2- (Sulfate ion)**:
- Sulfur (S) has 6 valence electrons.
- In SO4^2-, sulfur is bonded to four oxygen atoms.
- Total electrons around S = 4 bonds × 2 electrons/bond = 8 electrons.
- Sulfur does not exceed 8 electrons, so SO4^2- is **not hypervalent**.

4. **ClF3 (Chlorine trifluoride)**:
- Chlorine (Cl) has 7 valence electrons.
- In ClF3, chlorine is bonded to three fluorine atoms.
- Total electrons around Cl = 3 bonds × 2 electrons/bond = 6 electrons + 1 lone pair (2 electrons) = 8 electrons.
- Chlorine does not exceed 8 electrons, so ClF3 is **not hypervalent**.

### Conclusion
Based on the analysis, none of the species listed are hypervalent as they all have 8 or fewer electrons around the central atom.