Which of the following are isoelectronics and isostructural ?

Options

A. `NO_(3)^(-),CO_(3)^(2-)`
B. `SO_(3),NO_(3)^(-)`
C. `ClO_(3)^(-),CO_(3)^(2-)`
D. `CO_(3)^(2-),ClO_(3)^(-)`

Answer

To determine which of the given species are isoelectronic and isostructural, we will follow these steps:

### Step 1: Understand the Definitions
- **Isoelectronic Species**: Species that have the same number of electrons.
- **Isostructural Species**: Species that have the same geometrical structure.

### Step 2: Analyze the Given Species
Let's consider the two species provided in the first option: NO3⁻ (nitrate ion) and CO3²⁻ (carbonate ion).

### Step 3: Calculate the Total Number of Electrons
1. **For NO3⁻**:
- Nitrogen (N) has 7 electrons (atomic number 7).
- Each Oxygen (O) has 8 electrons, and there are 3 Oxygens: 3 × 8 = 24 electrons.
- The negative charge (1⁻) adds 1 more electron.
- Total electrons = 7 (N) + 24 (O) + 1 (negative charge) = 32 electrons.

2. **For CO3²⁻**:
- Carbon (C) has 6 electrons (atomic number 6).
- Each Oxygen (O) has 8 electrons, and there are 3 Oxygens: 3 × 8 = 24 electrons.
- The negative charge (2²⁻) adds 2 more electrons.
- Total electrons = 6 (C) + 24 (O) + 2 (negative charge) = 32 electrons.

### Step 4: Compare the Total Number of Electrons
Both NO3⁻ and CO3²⁻ have 32 electrons, thus they are **isoelectronic**.

### Step 5: Determine the Geometrical Structure
1. **For NO3⁻**:
- Nitrogen forms three bonds with three Oxygens.
- There are no lone pairs on Nitrogen.
- The hybridization is sp² (3 bond pairs, 0 lone pairs).
- The geometrical shape is **trigonal planar**.

2. **For CO3²⁻**:
- Carbon forms three bonds with three Oxygens.
- There are no lone pairs on Carbon.
- The hybridization is also sp² (3 bond pairs, 0 lone pairs).
- The geometrical shape is **trigonal planar**.

### Step 6: Conclusion
Since both NO3⁻ and CO3²⁻ are isoelectronic (32 electrons) and isostructural (both are trigonal planar), the first option is correct.

### Final Answer
NO3⁻ and CO3²⁻ are isoelectronic and isostructural species.

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