The correct increasing order of the ionic radii is

Options

A. `Ca^(2+)ltK^(+)ltCl^(-)ltS^(2-)`
B. `S^(2-)ltCl^(-)ltCa^(2+)ltK^(+)`
C. `K^(+)ltS^(2-)ltCa^(2+)ltCl^(-)`
D. `Cl^(-)ltCa^(2+)ltK^(+)ltS^(2-)`

Answer

To determine the correct increasing order of ionic radii among the given ions (Ca²⁺, K²⁺, Cl²⁻, S²⁻), we can follow these steps:

### Step 1: Understand the Ionic Charges
- **Cations** (positively charged ions) are formed when atoms lose electrons. The more positive the charge, the smaller the ionic radius due to increased effective nuclear charge pulling the remaining electrons closer to the nucleus.
- **Anions** (negatively charged ions) are formed when atoms gain electrons. The more negative the charge, the larger the ionic radius due to increased electron-electron repulsion.

### Step 2: Analyze the Given Ions
- **Ca²⁺**: Calcium loses 2 electrons, resulting in a smaller ionic radius.
- **K²⁺**: Potassium loses 2 electrons as well, but it has a larger atomic radius than calcium, so K²⁺ will still be larger than Ca²⁺.
- **Cl²⁻**: Chlorine gains 2 electrons, resulting in a larger ionic radius than its neutral atom.
- **S²⁻**: Sulfur gains 2 electrons, resulting in a larger ionic radius than its neutral atom, and it will be larger than Cl²⁻ due to the increased electron-electron repulsion.

### Step 3: Compare the Ionic Sizes
- The order of ionic sizes based on the charge and the original atomic sizes is as follows:
- **S²⁻** (largest, due to gaining 2 electrons)
- **Cl²⁻** (next largest, also gaining electrons)
- **K²⁺** (larger than Ca²⁺ due to being a group 1 element)
- **Ca²⁺** (smallest, due to losing 2 electrons)

### Step 4: Write the Increasing Order of Ionic Radii
Based on the analysis, the correct increasing order of ionic radii is:
**Ca²⁺ < K²⁺ < Cl²⁻ < S²⁻**

### Final Answer
The correct increasing order of the ionic radii is:
**Ca²⁺ < K²⁺ < Cl²⁻ < S²⁻**

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