Antimony Antimony Antimony is a chemical element with symbol Sb (from ) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (SbS). Antimony compounds have been known since ancient times and were powdered for use as medicine and cosmetics, often known by the Arabic name, kohl. Metallic antimony was also known, but it was erroneously identified as lead upon its discovery. The earliest known description of the metal in the West was written in 1540 by Vannoccio Biringuccio. For some time, China has been the largest producer of antimony and its
Silicon gas configuration of argon by forming sp hybrid orbitals, forming tetrahedral SiX derivatives where the central silicon atom shares an electron pair with each of the four atoms it is bonded to. The first four ionisation energies of silicon are 786.3, 1576.5, 3228.3, and 4354.4 kJ/mol respectively; these figures are high enough to preclude the possibility of simple cationic chemistry for the element. Following periodic trends, its single-bond covalent radius of 117.6 pm is intermediate between those of carbon (77.2 pm) and germanium (122.3 pm). The hexacoordinate ionic radius of silicon may be considered to be 40 pm, although this