Why alkaline earth metal carbonates trend of solubility decreases from top to bottom?

The solubility of alkaline earth metal carbonates decreases from top to bottom due to the increasing size and decreasing charge density of the metal cations. As you move down the group, the larger cations (like Ba²⁺) have a weaker attraction to the carbonate anion (CO₃²⁻), making it less energetically favorable for them to dissolve in water. Additionally, the lattice energy of the carbonates increases at a slower rate than the hydration energy, leading to lower solubility for the heavier alkaline earth metals.