GROUP 2: ALKALINE EARTHS

The elements known commonly as alkaline earths have atoms with the (ns)2 design and almost always have the +2 oxidation state in their compounds. Molecules such as MgH may be detected at bigger temperatures in the gas phase, the instability of the +1 state under normal conditions being due to the much larger lattice energies obtained with M2+. Some data explaining the factors underlying group trends are defined. Beryllium is unique, as the polarizing and very small Be2+ ion builds compounds with more covalent character than with the other elements, where a bigger degree of ionic character is normal. Be gives some similarities both with its diagonal neighbor aluminum, and with the group 12 element zinc.

Magnesium and calcium are very abundant elements, being distinct in silicate minerals and occurring in major deposits of CaMg(CO3)2 (dolomite), CaCO3 and MgKCl3.3H2O (carnallite). Phosphate and calcium fluoride minerals are the major sources of the substance P and F, respectively.