Period 5 element with most production coming from the Xikuangshan Mine in Hunan. Antimony compounds are prominent additives for chlorine and bromine containing fire retardants found in many commercial and domestic products. The largest application for metallic antimony is as alloying material for lead and tin. It improves the properties of the alloys which are used as in solders, bullets and ball bearings. An emerging application is the use of antimony in microelectronics. Tellurium is a chemical element that has the symbol Te and atomic number 52. A brittle, mildly toxic, rare, silver-white metalloid which looks similar to tin, tellurium is chemically related
Germanium transistors and various other electronic devices. Historically, the first decade of semiconductor electronics was based entirely on germanium. Today, the amount of germanium produced for semiconductor electronics is one fiftieth the amount of ultra-high purity silicon produced for the same. Presently, the major end uses are fibre-optic systems, infrared optics, solar cell applications, and light-emitting diodes (LEDs). Germanium compounds are also used for polymerization catalysts and have most recently found use in the production of nanowires. This element forms a large number of organometallic compounds, such as tetraethylgermane, useful in organometallic chemistry. Germanium is not thought to be an essential