Structures+-+Monica

Describe the structure of and bonding in silicon and silicon dioxide

Structure of silicon: Number of electrons: 14 Electron configuration: 2,8,4

Form a face-centered diamond cubic crystal structure.

Bonding in silicon: Has four bonding electrons, like carbon - gives it ability to combine with other elements or compounds.

Structure of silicon dioxide: 4 Oxygen atoms surrounding a central silicon atom Tetrahedral Bonding in silicon dioxide: Covalent bonds

hP9, P3121 No.152[|[][|12][|]] || Helical chains making individual single crystals optically active; α-quartz converts to β-quartz at 846 K || || hP18, P6222, No.180[|[][|13][|]] || closely related to α-quartz (with an Si-O-Si angle of 155°) and optically active; β-quartz converts to β-tridymite at 1140 K || || oS24, C2221, No.20[|[][|14][|]] || metastable form under normal pressure || || hP12, P63/mmc, No. 194[|[][|14][|]] || closely related to α-tridymite; β-tridymite converts to β-cristobalite at 2010 K || || tP12, P41212, No. 92[|[][|15][|]] || metastable form under normal pressure || || cF104, Fd__ 3 __m, No.227[|[][|16][|]] || closely related to α-cristobalite; melts at 1978 K || || cF576, Fd__ 3 __m, No.227[|[][|17][|]] || [|sodalite] cages connected by hexagonal prisms; 12-membered ring pore opening; faujasite structure.[|[][|9][|]] || || tP36, P41212, No. 92[|[][|20][|]] || Si5O10, Si4O14, Si8O16 rings; synthesised from glassy silica and alkali at 600–900K and 40–400 MPa || || mS46, C2/c, No.15[|[][|21][|]] || Si4O8 and Si6O12 rings || || mS48, C2/c, No.15[|[][|22][|]] || Si4O8 and Si8O16 rings; 900 K and 3–3.5 GPa || || tP6, P42/mnm, No.136[|[][|23][|]] || One of the densest (together with seifertite) polymorphs of silica; rutile-like with 6-fold coordinated Si; 7.5–8.5 GPa || || oP12, Pnc2, No.30[|[][|24][|]] ||  ||  || oI12, Ibam, No.72[|[][|25][|]] || like SiS2 consisting of edge sharing chains || || oP, Pbcn[|[][|26][|]] || One of the densest (together with stishovite) polymorphs of silica; is produced at pressures above 40 GPa.[|[][|27][|]] || ||
 * α-quartz || [|rhombohedral] (trigonal)
 * β-quartz || [|hexagonal]
 * [|α-tridymite] || [|orthorhombic]
 * β-tridymite || hexagonal
 * [|α-cristobalite] || [|tetragonal]
 * β-cristobalite || [|cubic]
 * [|faujasite] || cubic
 * [|melanophlogite] || cubic (cP*, P4232, No.208)[|[][|4][|]] or tetragonal (P42/nbc)[|[][|18][|]] || Si5O10, Si6O12 rings; mineral always found with hydrocarbons in interstitial spaces-a clathrasil[|[][|19][|]] || [[image:http://upload.wikimedia.org/wikipedia/en/thumb/a/ac/MelanophlogiteStucture.png/100px-MelanophlogiteStucture.png width="100" height="100" caption="MelanophlogiteStucture.png" link="http://en.wikipedia.org/wiki/File:MelanophlogiteStucture.png"]] ||
 * [|keatite] || tetragonal
 * [|moganite] || [|monoclinic]
 * coesite || monoclinic
 * stishovite || Tetragonal
 * [|poststishovite] || orthorhombic
 * fibrous || orthorhombic
 * seifertite || orthorhombic