33 10 Silicates . Introduction Silicates are compounds that mainly composed of [SiO4 It is the essential components of most rock and soil, such as quartz, feldspar, mica etc
§3.10 Silicates ◆ Ⅰ.Introduction Silicates are compounds that mainly composed of [SiO4 ]. It is the essential components of most rock and soil, such as quartz, feldspar, mica etc
I Features 1. Basic sell: [SIo4l rro=0.40/1.35=0.30<0.414 4 [Si04]4 Sioa tetrahedron
◆ Ⅱ.Features 1. Basic sell: [SiO4 ] rsi/rO＝0.40/1.35＝0.30<0.414 [SiO4] 4- 4－ SiO4 tetrahedron
Si+ is the cation that have small radii and large electrovalence The distance between si and o Si-O: 1.6 A(practical)<1.75 A(theoretic (0.40+1.35)
Si4+ is the cation that have small radii and large electrovalence. The distance between Si and O: Si－O : 1.6 Å(practical) < 1.75 Å (theoretic) (0.40+1.35)
2. The bonds of Si-o-Si is not beeline but zigzag Ine The angle of oxygen point is 1450 in silicate 3. For every oxygen, there is at most two SIO4 tetrahedrons can share it 4. The sio tetrahedrons can exist isolated or connect each other at common point
2. The bonds of Si-O-Si is not beeline but zigzag line. The angle of oxygen point is 145º in silicate. 3. For every oxygen, there is at most two SiO4 tetrahedrons can share it. 4. The SiO4 tetrahedrons can exist isolated or connect each other at common point
5. In silicate structure replace SIO4 aluminum-oxygen tetrahedrons aluminum-silicate aluminum oxygen aluminum-oxygen So, the cn of aluminum could be 4 or 6 6. The chemic expression or mineral molecular formula: AL2O3 2SiO2 H,O, Zro2 SiO2 structural formula: AL2SiO5(OH)4, Zrlsio
5. In silicate structure: So, the CN of aluminum could be 4 or 6 6. The chemic expression or mineral. molecular formula : Al2O3·2SiO2·H2O ; ZrO2·SiO2 structural formula : Al2 [Si2O5 ](OH)4 ; Zr[SiO4 ] aluminum + oxygen aluminum-oxygen tetrahedrons replace SiO4 tetrahedrons aluminum-silicate aluminum-oxygen octahedron