The atomic radii of `Cs^(+) and Cl^(-)` ions are `1.69 Å and 1.81 Å` respectively. Predict the coordination number of `Cs^(+)` ion and structure of CsCl.

Explanation

To solve the question regarding the coordination number of the Cs⁺ ion and the structure of CsCl, we will follow these steps:

### Step 1: Identify the given data
We are given the atomic radii of the ions:
- Atomic radius of Cs⁺ = 1.69 Å
- Atomic radius of Cl⁻ = 1.81 Å

### Step 2: Calculate the radius ratio
The radius ratio (r) can be calculated using the formula:
\[ r = \frac{R_{cation}}{R_{anion}} \]

Substituting the values:
\[ r = \frac{1.69 \, \text{Å}}{1.81 \, \text{Å}} \]

### Step 3: Perform the calculation
Calculating the radius ratio:
\[ r = \frac{1.69}{1.81} \approx 0.934 \]

### Step 4: Determine the coordination number using the radius ratio
Using the radius ratio, we can refer to the radius ratio rules to determine the coordination number. The ranges for coordination numbers based on the radius ratio are as follows:
- \( r < 0.155 \): Coordination number = 2 (linear)
- \( 0.155 < r < 0.225 \): Coordination number = 3 (triangular planar)
- \( 0.225 < r < 0.414 \): Coordination number = 4 (tetrahedral)
- \( 0.414 < r < 0.732 \): Coordination number = 6 (octahedral)
- \( 0.732 < r < 1 \): Coordination number = 8 (cubic)

Since \( r \approx 0.934 \), it falls in the range \( 0.732 < r < 1 \), which corresponds to a coordination number of 8.

### Step 5: Determine the structure of CsCl
Based on the coordination number of 8, we can conclude that the structure of CsCl is cubic. In a cubic structure, each Cs⁺ ion is surrounded by 8 Cl⁻ ions and vice versa.

### Final Answer
- Coordination number of Cs⁺ = 8
- Structure of CsCl = Cubic