Silicon

Silicon (Si = 28) is a non-metallic element which was first prepared by Berzelius in 1810. It is only prepared with difficulty, although its compounds are very abundant. Next to oxygen it is the most abundant element in the earth's crust, occurring, however, always in the combined state as silica or silicates. It may be obtained as a brown powder which burns if heated, forming the oxide silica. It may also be obtained in a crystalline form as black hexagonal tablets, somewhat resembling graphite, and also as octahedral crystals. It unites with hydrogen to form a gaseous hydride, and forms interesting chlorides, bromidrs, and iodides. In its chemical deportment it exhlbits many striking similarities to carbon. Many organic compounds containing carbon thus are represented amongst silicon compounds, the only constitutional difference being the replacement of carbon by silicon. Thus silico chloroform (SiHCl₃) corresponds to chloroform (CHCl₃), etc. Its oxide is known as silica (q.v.), and forms the basis of a large number of compounds known as silicates (q.v.).