Final answer:
Barium, a Group 2 metal, forms compounds such as barium sulfate that are known for their low solubility in water. The tendency for lower solubility of such compounds increases down the Group 2 elements.
Step-by-step explanation:
The Group 2 metal that forms compounds with low solubility is typically barium (Ba). Group 2 metals are known as the alkaline earth metals and have a tendency to form less soluble hydroxides and sulfates compared to Group 1 metals due to their charge density.
Among the alkaline earth metals, the solubility of hydroxides and sulfates decreases down the group, with barium sulfate (BaSO4) being an example of a compound that is notably insoluble in water. This is due to the fact that Ba2+ ions form stronger ionic bonds with the sulfate ions, resulting in a lower solubility.
The Group 2 metals form compounds with low solubility. These metals include beryllium, magnesium, calcium, strontium, barium, and radium.
The low solubility is due to the high lattice energy of these compounds, which requires significant energy to break the strong electrostatic interactions between the ions in the solid state.
For example, calcium sulfide (CaS) is a compound with low solubility. When calcium ions (Ca²⁺) and sulfide ions (S²⁻) combine, they form a lattice structure that is difficult to dissolve in water.
Other examples of Group 2 compounds with low solubility include strontium sulfate (SrSO₄) and barium carbonate (BaCO₃).