10.1.4—Describe, and make predictions

Down Group 2, ionic radius increases while charge remains +2. Charge density therefore decreases, affecting hydration, lattice interactions, solubility and thermal stability.

Link a prediction to the relevant process: lower polarisation stabilises oxyanions, while hydration and lattice-energy changes determine solubility trends.

Ba²⁺ is larger than Mg²⁺, so BaCO₃ is more thermally stable. Hydroxide solubility rises down the group, whereas sulfate solubility falls.

Not every property changes in the same direction. State which competing energies control the particular trend instead of applying one arrow to all compounds.