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Johnsenite-(Ce) is a very rare mineral of the eudialyte group, [2] with the chemical formula Na 12 (Ce,La,Sr,Ca,[ ]) 3 Ca 6 Mn 3 Zr 3 WSi(Si 9 O 27) 2 (Si 3 O 9) 2 (CO 3)O(OH,Cl) 2. [3] The original formula was extended to show the presence of both the cyclic silicate groups and silicon at the M4 site, according to the nomenclature of the eudialyte group. [4]
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With two shared oxides bound to each silicon, cyclic or polymeric structures can result. The cyclic metasilicate ring Si 6 O 12− 18 is a hexamer of SiO 3 2-. Polymeric silicate anions of can exist also as long chains. In single-chain silicates, which are a type of inosilicate, tetrahedra link to form a chain by sharing two oxygen atoms each.
During a time of high uplift rate, silicate weathering increases which results in high CO 2 uptake rates, offsetting increased volcanic CO 2 emissions associated with the geologic activity. This balance of weathering and volcanoes is part of what controls the greenhouse effect and ocean pH over geologic time scales.
Zirsilite-(Ce) is a very rare mineral of the eudialyte group, with formula (Na, ) 12 (Ce,Na) 3 Ca 6 Mn 3 Zr 3 NbSi(Si 9 O 27) 2 (Si 3 O 9) 2 O(OH) 3 (CO 3)·H 2 O. [2] [3] The original formula was extended to show the presence of cyclic silicate groups and the presence of silicon at the M4 site, according to the nomenclature of the eudialyte group. [4]
A silicate mineral is generally an inorganic compound consisting of subunits with the formula [SiO 2+n] 2n−. Although depicted as such, the description of silicates as anions is a simplification. Balancing the charges of the silicate anions are metal cations, M x+. Typical cations are Mg 2+, Fe 2+, and Na +. The Si-O-M linkage between the ...
Hydrolysis of a silyldichloride can afford linear or cyclic products. Linear products are terminated with silanol groups: n R 2 Si(OH) 2 → H(R 2 SiO) n OH + (n − 1) H 2 O. Cyclic products have no silanol termini: n R 2 Si(OH) 2 → (R 2 SiO) n + n H 2 O. The linear products, polydimethylsiloxane (PDMS), are of great commercial value.
Silicon compounds are compounds containing the element silicon (Si). As a carbon group element, silicon often forms compounds in the +4 oxidation state, though many unusual compounds have been discovered that differ from expectations based on its valence electrons, including the silicides and some silanes.