Group 2 carbonates become more thermally stable as you move down the group.

This trend is due to the increasing polarising power of the group 2 cation, which weakens the bonds in the carbonate ion to a greater extent.

The polarising power of a cation is a measure of its ability to polarise nearby anions.

Ion polarisation is the distortion of the electron cloud around an anion caused by the electric field of a nearby cation attracting the electrons.

A compond is likely to be soluble in water only if Δ_solH^⦵ is negative or has a small positive value.

Compounds with large postive values of Δ_solH^⦵ are relatively insoluble. 

The solubility of group 2 sulfates decreases as you move down the group.

This is because:

1. Lattice energy and enthalpy change of hydration decrease as we move down the the group due to the decreasing charge density of the group 2 cation.
2. The sulfate ion makes a greater contribution to the lattice energy compared to the group 2 cation because it is a larger ion.
3. This means that lattice energy decreases by a smaller amount than the enthalpy change of hydration as we move down the group.
4. Δ_solH^⦵ becomes more positive (endothermic) as we move down the group.

The solubility of group 2 hydroxides increases as you move down the group.

This is because:

1. Lattice energy and enthalpy change of hydration decrease as we move down the group due to the decreasing charge density of the group 2 cation.
2. The group 2 cation makes a greater contribution to the lattice energy compared to the hydroxide ion because the group 2 cation is a larger ion.
3. This means that lattice energy decreases by a greater amount than the enthalpy change of hydration as we move down the group.
4. Δ_solH^⦵ becomes more negative (exothermic) as we move down the group.

1Lattice energy.

2Enthalpy change of hydration of the cation.

3Enthalpy change of hydration of the cation.

Group 2 nitrates become more thermally stable as you move down the group.

This trend is due to the increasing polarising power of the group 2 cation, which weakens the bonds in the nitrate ions to a greater extent.

Δ_solH^⦵ = Δ_hydH^⦵ - Δ_lattH^⦵