Barium Barium is the 14th most common element of the Periodic Table of Elements. It makes up 1/2000th of the crust of the earth. Its atomic number is 56, and its atomic symbol is Ba. The atomic weight of Barium is 137.34. Barium is a silver-colored metal. Barium is in group 2 (or IIa) of the periodic table. It belongs to the alkaline earth group. The melting point of Barium is 725 degrees C, and its boiling point is 1640 Degrees C. It has a specific gravity of 3.51 g/cm. Barium is a metallic element. Some of its properties are that it is heavy, highly reactive, soft, and when pure it is silvery white like lead. It is slightly harder