Chemical elements
    Physical Properties
    Chemical Properties
      Silicon Tetrahydride
      Silicon Tetrafluoride
      Hydrofluosilicic Acid
      Silicon Subfluoride
      Silicon Tetrachloride
      Silicon Tetrabromide
      Silicon Tetra-iodide
      Mixed Halides of Silicon
      Halogen Derivatives of Silico-ethane
      Halogen Derivatives of Silicopropane
      Halogen Derivatives of Silicobutane
      Halogen Derivatives of Silicopentane and Silicohexane
      Silicon Oxychlorides
      Silicon Dioxide
      Silicoformic Anhydride
      Silico-oxalic Acid
      Silicomes-oxalic Acid
      Silicon Disulphide
      Silicon Monosulphide
      Silicon Oxysulphide
      Silicon Thiochloride
      Silicon Thiobromide
      Silicon Chloroitydrosulphide
      Silicon Selenide
      Silicon Tetramide
      Silicon Di-imide
      Silicon Nitrimide
      Siliconitrogen Hydride
      Silicon Nitrides
      Crystalline Silicon Monocarbide
      Silicon Dicarbide
      Silicon Carboxide
      Borides of Silicon
    PDB 1fuq-4ehr

Chemical Properties of Silicon

Silicon forms with boron and carbon a little group of non-metals, which in the elementary state are characterised by distinct allotropy accompanied by high molecular complexity, so that not only are the elements non-volatile, even at high temperature, but they are, for the same reason, comparatively inert towards chemical reagents. Silicon in combination, like carbon, is almost invariably quadrivalent; though it appears that silica is reducible to a lower state of oxidation in which the element is bivalent. Silicon is one of the least electronegative of the non- metals, and forms compounds with other non-metals more readily than with metals; moreover, silicic acid is a very weak acid, and shares with boric, stannic, and some other acids the tendency to form condensed acids.

Silicon is the second member of the fourth group of the Periodic system; thus it occupies a position in the centre of the second short period. Like its neighbours in this period, it shows a relationship to the first member of the group - in this case carbon - which is by no means close, since all the members of the first short period show unique characteristics, which separate them from the rest of the elements. Especially is this the case with carbon, to which silicon, even with oar extending knowledge of its capabilities, will probably never be found to bear any close relationship. The relationship between silicon and other elements has been fully discussed in the introductory chapter.

Detection and Estimation of Silicon

The silicon present in a compound of this element is invariably detected and estimated in the form of silica, which is identified by the microcosmic or sodium carbonate bead test. In the former test the silica floats uncombined with the sodium metaphosphate in the clear bead of this substance formed by fusing microcosmie salt; in the latter test silica, by forming a glass, renders transparent the otherwise crystalline and opaque bead of sodium carbonate. The silica may be obtained, sometimes by hydrolysing the compound with water, by fusing it with a mixture of sodium and potassium carbonates and decomposing the resulting silicates with hydrochloric acid, or else by heating it with concentrated sulphuric acid. This latter method is useful for estimating the silicon in an organic compound; the acid burns up all the carbon and leaves a residue of pure silica.
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