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Silicon is a metalloid and has the second most abundance in earth crust after oxygen, It is not found in elemental form. It forms 95 % of the rocks in.

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Presentation on theme: "Silicon is a metalloid and has the second most abundance in earth crust after oxygen, It is not found in elemental form. It forms 95 % of the rocks in."— Presentation transcript:

1 Silicon is a metalloid and has the second most abundance in earth crust after oxygen, It is not found in elemental form. It forms 95 % of the rocks in the earth. It is found in compounds such as silica, SiO 2, and silicates SiO 2 is found as sand, quartz and mountain crystals in nature. Occurrence of Silicon

2 Preparation Heating silica with coke at C in electric furnaces. SiO 2 (s) + 2C(s) → Si(s) + 2CO(g) SiCl 4 is heated with H 2 or metals. SiCl 4 (g) + 2H 2 (g) → Si(s) + 4HCl(g) SiCl 4 (g) + 4Na(s) → Si(s) + 4NaCl(s) With strong reducing gents like Cu, Mg and CaCl 2. SiO 2 (s) + 2Mg(s) → Si(l) + 2MgO(s) Heat 800 o C o C

3 Chemical Properties of Silicon Reactions React with C, O, S and N at high temperatures ( C) Si + O 2 → SiO 2 Si + C → SiC Reacts with halogens. Si(s) + 2F 2 (g) → SiF 4 (g) Si(s) + 2Cl 2 (g) → SiCl 4 (g) React with HF (not other acids) Si + 4HF → SiF 4 + 2H 2 React with hot strong base solutions. Si + 2KOH + H 2 O → K 2 SiO 3 + 2H 2

4 Silicon Dioxide, SiO 2 It has similar structure to diamond, 57% of Earth crust is SiO2 and silicates. Used to make jeweler, laboratory glassware, various lenses, ultraviolet light-passing glass, fluorescent lamps, light-sensitive electrical measurement instruments and glassware. It does not dissolve in water or acids (except HF). SiO 2 (s) + 4HF(g) → 2H 2 O(l) + SiF 4 (g) SiO 2 is a stable compound. React only strong reducing agents. SiO 2 (s) + 2Mg(s) → Si(s) + 2MgO(s)

5 Silicates They are composed of SiO 2 and metal oxides Clay: Occurs naturally as alumina silicate, H 4 Al 2 SiO 9. They can be shaped easily when they are wet. Used to prepare pottery, cement, ceramics, rubber and paint. It is a hard substance, when cooled it solidifies, without crystallization and quartz glass is formed.

6 Glass: The main component of glass are sodium silicate,Na 2 SiO 3, and calcium silicate,CaSiO 3. Glass is hard, brittle, amorphous, transparent, not affected by chemically active substances. Formula of ordinary glass, Na 2 O.CaO.6SiO 2.

7 Cement: Main component is calcium aluminosilicate. It is used in concrete which is mixture of cement, sand, and stone.

8 Silicones Polymeric compounds have properties of both hydrocarbons and silicon-oxygen compounds. They are odorless, colorless, inert They are used in hydraulic fluids, enamels, sealing compounds, varnishes, resins and synthetic rubber.

9 Uses of Silicon In polymers, solar cells, different alloys, cement, glass, clay, jeweler industry…etc.


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