Describe the differences between the reactivity and solubility of Group 2 elements.

Group 2 elements differ in their reactivity and solubility due to variations in their atomic structure.

Reactivity:

The reactivity of Group 2 elements increases down the group. This is because the outermost electrons are located in higher energy levels further from the nucleus, making them easier to lose. As a result, the elements become more reactive with water and oxygen as you move down the group. For example, magnesium reacts slowly with cold water, while barium reacts vigorously. This trend can be observed in the reactivity series.

Solubility:

The solubility of Group 2 elements also varies down the group. The solubility of the hydroxides and sulfates of Group 2 elements decreases as you move down the group. This is because the ionic radius of the cation increases, making it more difficult for water molecules to surround and dissolve the ions. For example, calcium hydroxide is more soluble than strontium hydroxide, which is more soluble than barium hydroxide. However, the solubility of the carbonates and nitrates of Group 2 elements increases down the group. This is because the carbonates and nitrates decompose upon heating to form the corresponding oxides, which are more soluble than the original compounds.

In summary, the reactivity and solubility of Group 2 elements are influenced by variations in their atomic structure, specifically the number of outermost electrons and ionic radius of the cation.