Silicates infinite sheet anions

There are also chloro complexes M Be h, M = K, Rb, NFL, that have p.-Cl atoms in a chain structure quite unlike the MIBe2F5 analogs that have infinite sheet anions in which there are hexagonal rings of BeF4 tetrahedra sharing comers (cf. silicate anions Si202-, Section 8-7). 

Infinite Sheet Anions. When Si04 tetrahedra are linked into infinite two-dimensional networks as shown in Fig. 11-4, the empirical formula for the anion is (Si205 ) . Many silicates have such sheet structures with the sheets bound together by the cations which lie between them. Such substances might thus be expected to cleave readily into thin sheets, and this expectation is confirmed in the micas which are silicates of this type. 

Fig. 16.1 Various silicate structure (a) Si04 tetrahedron. When carrying a —4 charge, this s the orthoslknte ion. (b) The dbalicalc anion- (c) Portion of an infinite single chain. (SiO ) "-- (d) Portion of an infinite double clcun or band. Si40,itff. (e) Portion of a sheet or layer structure. (Si2Oj 2, —.

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