alkaline-earth metals

The elements of group 2 (formerly called group IIa in North America and IIb in Europe) include the metals beryllium, magnesium, calcium, strontium, barium, and radium. Three of these elementsócalcium, strontium and barium-and sometimes beryllium, magnesium and radiumóare collectively known as the alkaline-earth metals: alkaline, because they all form strong alkaline solutions, or bases; earths, because of the insolubility and incombustibility of their oxides. Although none of the alkaline-earth metals occur in nature as pure metals, compounds containing magnesium and calcium abound in the Earth's crust.