The correct order of hydration energy of alkaline earth metal ions is

Options

A. `Be^(+2) gt Mg^(+2) gt Ca^(+2) gt Sr^(+2) gt Ba^(+2)`
B. `Ba^(+2) gt Be^(+2) gt Ca^(+2) gt Mg^(+2) gt Sr^(+2)`
C. `Mg^(+2) gt Be^(+2) gt Ba^(+2) gtCa^(+2) gt Sr^(+2)`
D. None

Answer

To determine the correct order of hydration energy of alkaline earth metal ions, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Hydration Energy**: Hydration energy refers to the energy released when ions are surrounded by water molecules. It is influenced by the charge of the ion and its size.

2. **Periodic Trend**: In the periodic table, alkaline earth metals are found in Group 2. As we move down the group from beryllium (Be) to barium (Ba), the size of the ions increases.

3. **Charge Density Consideration**: All alkaline earth metal ions have a +2 charge. However, as the ionic radius increases down the group, the charge density (charge per unit volume) decreases. This is because larger ions have a lower charge density.

4. **Effect on Hydration Energy**: Higher charge density leads to stronger interactions with water molecules, resulting in higher hydration energy. Therefore, smaller ions with higher charge density will have higher hydration energies.

5. **Order of Hydration Energy**: Based on the above points, the order of hydration energy for alkaline earth metal ions from highest to lowest is:
- Beryllium (Be²⁺) > Magnesium (Mg²⁺) > Calcium (Ca²⁺) > Strontium (Sr²⁺) > Barium (Ba²⁺)

6. **Final Answer**: Thus, the correct order of hydration energy of alkaline earth metal ions is:
- Be²⁺ > Mg²⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺