To determine which pairs of ions are isoelectronic and isostructural, we need to follow these steps:
### Step 1: Define Isoelectronic and Isostructural
- **Isoelectronic**: Ions that have the same number of electrons.
- **Isostructural**: Ions that have the same hybridization and molecular geometry.
### Step 2: Calculate the Total Number of Electrons for Each Ion
1. **SO₃²⁻ (Sulfite Ion)**:
- Sulfur (S) has an atomic number of 16, contributing 16 electrons.
- Each Oxygen (O) has an atomic number of 8, and there are 3 Oxygens contributing 24 electrons.
- The 2 negative charge adds 2 electrons.
- Total electrons = 16 + 24 + 2 = **42 electrons**.
2. **NO₃⁻ (Nitrate Ion)**:
- Nitrogen (N) has an atomic number of 7, contributing 7 electrons.
- Each Oxygen (O) has an atomic number of 8, and there are 3 Oxygens contributing 24 electrons.
- The 1 negative charge adds 1 electron.
- Total electrons = 7 + 24 + 1 = **32 electrons**.
3. **ClO₃⁻ (Chlorate Ion)**:
- Chlorine (Cl) has an atomic number of 17, contributing 17 electrons.
- Each Oxygen (O) has an atomic number of 8, and there are 3 Oxygens contributing 24 electrons.
- The 1 negative charge adds 1 electron.
- Total electrons = 17 + 24 + 1 = **42 electrons**.
4. **CO₃²⁻ (Carbonate Ion)**:
- Carbon (C) has an atomic number of 6, contributing 6 electrons.
- Each Oxygen (O) has an atomic number of 8, and there are 3 Oxygens contributing 24 electrons.
- The 2 negative charge adds 2 electrons.
- Total electrons = 6 + 24 + 2 = **32 electrons**.
### Step 3: Determine Steric Number and Hybridization
- **Steric Number Formula**: Steric number = Number of bond pairs + Number of lone pairs.
1. **SO₃²⁻**:
- Bond pairs: 3 (with O)
- Lone pairs: 1 (on S)
- Steric number = 3 + 1 = **4** (Hybridization: sp³, Shape: Pyramidal).
2. **NO₃⁻**:
- Bond pairs: 3 (with O)
- Lone pairs: 0
- Steric number = 3 + 0 = **3** (Hybridization: sp², Shape: Trigonal planar).
3. **ClO₃⁻**:
- Bond pairs: 3 (with O)
- Lone pairs: 1 (on Cl)
- Steric number = 3 + 1 = **4** (Hybridization: sp³, Shape: Pyramidal).
4. **CO₃²⁻**:
- Bond pairs: 3 (with O)
- Lone pairs: 0
- Steric number = 3 + 0 = **3** (Hybridization: sp², Shape: Trigonal planar).
### Step 4: Compare the Results
- **SO₃²⁻** and **ClO₃⁻**: Both have 42 electrons, sp³ hybridization, and pyramidal shape.
- **NO₃⁻** and **CO₃²⁻**: Both have 32 electrons, sp² hybridization, and trigonal planar shape.
### Conclusion
The pairs of ions that are isoelectronic and isostructural are:
- **SO₃²⁻ and ClO₃⁻** (both have 42 electrons and pyramidal shape).
- **NO₃⁻ and CO₃²⁻** (both have 32 electrons and trigonal planar shape).
### Final Answer
- The correct pairs are **(SO₃²⁻, ClO₃⁻)** and **(NO₃⁻, CO₃²⁻)**.
