The symbol "Sb" that stands for the element Antimony comes from the Latin word "stibium"; antimony sulfide had stibium as its ancient name. The word "stibium" means a mark. The element has the Atomic number of fifty one and the Atomic Mass of 121.76 amu. Antimony has a melting point of six hundred and thirty degrees Celsius and a boiling point of one thousand seven hundred and fifty degrees. Antimony has fifty one protons/electrons and the number of neutrons is seventy one. The element Antimony is classified as a metalloid and has a rhombohedral crystal structure. Its colour is bluish. The element has been known since ancient times though its discoverer is not known. Antimony is generally used for hardening plastics, lead and chemicals.