Beryllium (Beryllium) is the second main group element of the second period, the atomic number is 4, the element symbol Be, is a gray-white alkaline earth metal, belongs to the hexagonal crystal system, hard, malleable. Both beryllium and its compounds are highly toxic. Beryllium can be soluble in both acid and lye, is an amphoteric metal, beryllium is mainly used in atomic reactor materials, aerospace engineering materials, various alloys, X-ray transmission windows, etc.