Group 2A of the Periodic table contains the Alkaline Earth metals. Those elements are Beryllium ( Be ), Magnesium ( Mg ), Calcium ( Ca ), Strontium ( Sr ), Barium ( Ba ) and Radium ( Ra ). Beryllium is the lightest member of the group 2A. Ionic radius increases moving down the group and decreases from left to right across the period of elements. In the group 2A, the ionic radius increases from Beryllium ( 59 pm - picometers ) to Radium ( 163 pm ). Beryllium has the lowest ionic radius.
Melting and freezing for a given
substance occurs at the same temperature. Because the temperature at which the
solid starts to melt is also the temperature at which the liquid starts to
freeze. They are at chemical equilibrium.