Physical properties of antimony

The four allotropic forms of antimony are known as grey, black, yellow, and explosive. The black, yellow, and explosive forms are unstable. Grey, the only stable form of antimony, is what is considered to be ordinary metallic antimony. It is silvery white and exhibits a bluish or purplish luster. Metallic antimony is naturally occurring. However, elemental antimony is rare to the point that it has no practical significance. The atomic weight is 121.75 and its atomic number is 51. The two stable isotopes are Sb¹²¹ and Sb¹²³. The smaller isotopes occurs 57.25% of the time while the larger occurs 42.75% of the time. The electron configuration of the outer valence shell is 5s²5p³. Antimony’s radius is ~0.150 nm. Finally, the atomic volume of antimony is 18.4 cm³/mol at 25° C.