The highest lattice energy corresponds to

Options

A. SrO
B. BaO
C. MgO
D. CaO

Answer

To determine which ionic compound has the highest lattice energy, we need to understand the concept of lattice energy and how it relates to ionic bonds.

### Step-by-Step Solution:

1. **Definition of Lattice Energy**:
Lattice energy is defined as the measure of the strength of the ionic bond in an ionic compound. It is the energy released when gaseous ions combine to form an ionic solid.

2. **Factors Affecting Lattice Energy**:
Lattice energy is influenced by two main factors:
- The charge of the ions: Higher charges on the ions lead to stronger attractions and thus higher lattice energy.
- The size of the ions: Smaller ions can get closer together, leading to stronger attractions and higher lattice energy.

3. **Comparing Ionic Compounds**:
In the case of the compounds mentioned (MgO, CaO, SrO, BaO), we need to consider both the ionic charges and the sizes of the ions. All these compounds consist of divalent cations (Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺) and O²⁻ anions.

4. **Order of Ionic Sizes**:
As we move down the group in the periodic table, the size of the cations increases:
- Mg²⁺ < Ca²⁺ < Sr²⁺ < Ba²⁺
This means that Mg²⁺ is the smallest and Ba²⁺ is the largest.

5. **Bond Length and Lattice Energy Relationship**:
- Smaller ions lead to shorter bond lengths, which results in stronger ionic bonds and higher lattice energy.
- Conversely, larger ions lead to longer bond lengths, which results in weaker ionic bonds and lower lattice energy.

6. **Conclusion**:
Based on the above factors, the order of lattice energies for the compounds is:
- MgO > CaO > SrO > BaO
Therefore, MgO has the highest lattice energy among the given options.

### Final Answer:
The highest lattice energy corresponds to **MgO (option C)**.