Chemistry – Inorganic chemistry | e-Consult

The reactivity of Group 2 metals increases down the group. This is because the ionization energy decreases down the group. Ionization energy is the energy required to remove an electron from an atom. As we move down the group, the outermost electrons are further from the nucleus and shielded by more inner electrons, making them easier to remove.

Beryllium (Be) has an electronic configuration of [He] 2s². It requires a significant amount of energy to remove these two electrons, resulting in a high ionization energy. Magnesium (Mg) has an electronic configuration of [Ne] 3s². Its ionization energy is lower than beryllium's because the 3s electrons are further from the nucleus and better shielded. Calcium (Ca) has an electronic configuration of [Ar] 4s². Its ionization energy is the lowest of the three, as the 4s electrons are even further from the nucleus and more shielded.

The trend in reactivity is directly related to ionization energy. Metals with lower ionization energies lose electrons more easily and therefore react more readily with non-metals. As you move down Group 2, the ionization energy decreases, leading to increasing reactivity. Beryllium is the least reactive, followed by magnesium, and then calcium. This is because it requires the most energy to remove its valence electrons.