GROUP 2: ALKALINE EARTHS

The elements

The elements known generally as alkaline earths have atoms with the (ns)² configuration and approximately all the time have the +2 oxidation state in their compounds. Molecules like MgH can be detected at high temperatures within the gas phase, the instability of the +1 state under normal circumstances being because of the much greater lattice energies acquired with M²⁺. Beryllium is different, as the extremely small and polarizing Be²⁺ ion creates compounds with more covalent character than with the another elements, in which a high degree of ionic character is general. Be depicts some similarities both with its diagonal neighbor aluminum and with the group no.12 element zinc.

Magnesium and Calcium are extremely abundant elements, being general in silicate minerals and taking place in main deposits of CaCO₃, CaMg(CO₃)₂ (dolomite) and MgKCl₃.3H₂O (carnallite). Phosphate minerals and calcium fluoride are the main sources of the elements P and F, correspondingly. The fairly abundant heavier elements are found mainly like sulfates SrSO₄ and BaSO₄, whereas beryllium is rather uncommon and take place in beryl Be₃Al₂Si₆O₁₈. Radium is radioactive, its longest-lived isotope ²²⁶Ra containing a half-life of 1600 years and being found in uranium minerals. Calcium and magnesium are main elements in life except beryllium and its compounds are extremely toxic.

The metallic elements are all extremely reactive in the direction of air, water and most elements, but Be and Mg create passivating oxide films. Elemental magnesium is created in large quantities either through electrolysis of molten MgCl₂ or through reduction of MgO, and is employed in lightweight alloys and like a reducing agent. The other elements are employed principally as compounds.