Radium electronic structure

This group contains the elements beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra). After the alkali metals, they are the second most active metals. Their electron configurations end with ns2. They become positive two charged ions by giving of their two valence electrons in chemical reactions. At room temperature, they occur in a monoatomic structure and they are solid at room temperature. Radium, a solid element, is the only radioactive member of this group. 

Thus, the structures of the elements above radon (element 86) through uranium were written to show the addition of the next two electrons in the 7s shell for element 87 (francium) and element 88 (radium) and addition in the 6d shell for actinium, thorium, protactinium and uranium (Latimer and Hildebrand 1940 Richtmeyer and Kennard 1942 Taylor and Glasstone 1942). 

Toward the end of his life, Berthelot (1827-1907) was able to show that amethyst, on heating, became colorless, but that the color could be restored by exposition to radium radiation [41]. Crystallographers today have discovered that color centers, structural flaws in the crystal lattice, are responsible for trapping or releasing energized electrons which can change the valencies of the interstitial iron impurities, thus yielding the colors. 

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