Alkaline earth metals: trends and anomalous behaviour of beryllium
s-Block Elements · Chemistry
Study notes
BeO is amphoteric but MgO is basic. Explain. Step 1: Be²⁺ is tiny (31 pm) → highly polarising → Be–O bonds have covalent character. Step 2: Covalent BeO reacts with both acids AND bases (amphoteric). Step 3: Mg²⁺ is larger → more ionic → MgO is straightforwardly basic. Step 4: Same pattern as Al₂O₃ (amphoteric) — Be's diagonal twin!