SILICONES SI

Silicones (SI) This is a group of materials differing in structure from the rest of organic compounds, due to the presence of the inorganic group Si-O-Si, based on silicon atoms Si which replace carbon in the main chain. The side groups, however, are paraffinic. 

Silicones appear in various compositions from thin fluids up to polymers that act as elastomers or thermosetting rigid plastomers. Silicones excel in weather durability, water repellency and in electrical and thermal properties. Silicone resins or coatings have heat-distortion temperatures up to 450 C. They are much used in aviation and the space industry as electrical insulation for motors, glue, protective coatings, a premium elastomer or as additives in construction. 

---

The Elements Beryllium (Be), Magnesium (Mg), and Calcium (Ca) all formed oxides in fhe ratio of one afom per oxygen atom RO Boron (B) and Aluminum (Al) formed R2O3 Carbon (C) and Silicon (Si) formed RO2... 

FIGURE B.12 The location ot the seven elements commonly regarded as metalloids these elements have characteristics of both metals and nonmetals. Other elements, notably beryllium and bismuth, are sometimes included in the classification. Boron (B), although not resembling a metal in appearance, is included because it resembles silicon (Si) chemically. 

Reaction of ammonia (NH3) with tetrakis (dimethylamido) silicon, Si(NMe2)4 at200-400°C. 

Deposition at low temperature (200 00°C) is possible by plasma-CVD from the reaction of ammonia and a metallo-organic precursor tetrakis(dimethylamido)silicon, Si(NMe2)4. The films are essentially featureless. 

Silicon (Si) is a nonmetallic chemical element of the carbon family (Group rva of the periodic table) and makes up 27.7 percent of the Earth s crust. It is the second most abundant element in the crust, being surpassed only by oxygen. 

---