Q.Explain the important common features of Group 2 elements.

Step 1. Electronic configuration and oxidation state: every group 2 element has the general valence configuration ns², and loses both electrons to reach a stable noble-gas configuration, giving a single, characteristic +2 oxidation state throughout the group.

Step 2. Bonding character: their compounds are predominantly ionic, but LESS so than the corresponding alkali metal compounds, because the higher nuclear charge and smaller ionic size of M²⁺ gives it more polarising power than M⁺.

Step 3. Size trends: atomic and ionic radii are smaller than the corresponding alkali metals of the same period (stronger nuclear pull on the valence electrons), but they still increase down group 2 itself, as extra shells are added.

Step 4. Ionisation behaviour: first ionisation enthalpy is higher than the corresponding alkali metal's (smaller size, stronger attraction, hence less electropositive overall) and falls down the group; unlike the alkali metals, though, the SECOND ionisation enthalpy is comparatively low, since the second electron is removed from a monovalent cation that still has one valence electron left, not from an already-stable noble-gas-like M⁺.

Step 5. Hydration and hardness: hydration enthalpies of the M²⁺ ions are larger in magnitude than the alkali metal M⁺ ions (giving more extensively hydrated compounds), and having two valence electrons contributing to metallic bonding makes the group 2 metals harder, with higher melting and boiling points, than the alkali metals. …

Systematically walk through configuration, oxidation state, bonding character, size trends, the two ionisation enthalpies, hydration, hardness and reactivity, comparing group 2 …

• Listing only the +2 oxidation state and stopping, without covering the size/ionisation/hydration/hardness/reactivity comparisons that 'important …