In the periodic table, the elements of group 2 i.e. Berillium, Magnesium, Calcium, Strontium, barium and Radium are known as alkaline earth metals. They are called so because they are generally found in earth’s crust.
Occurrence : Alkaline earth metals are not found in free state generally because they are very reactive. Beryllium is generally found as silicate minerals like beryl (Be3Al2Si6O18) etc.
Magnesium is found in abundance. It is the sixth most abundant element in earth’s crust by weight. It is found in the form of minerals like carnallite (KCl.MgCl2.6H2O), magnesite (MgCO3) etc.
Calcium is another very abundant element of this group. According to abundance, it is the 5th element by weight. Its main sources are limestone, marble and chalk. Some other minerals of calcium are also available like fluorspar(CaF2), gypsum(CaSO4.2H2O) and anhydride(CaSO4).
Strontium is found as celestite(SrSO4) and strontianite(SrCO3).
Barium is found as barytes(BaSO4).
Radium is a radioactive substance and it is rare.
Electronic configuration : The outer shell electronic configuration of alkaline earth metals is ns2.