These are all three dimensional frameworks, it does not include several other ways to connect the tetrahedrons, such as sheets or chains. With other elements it has different structures, for instance faujasite, with a “slightly” more complex formula (Na 2, Ca, Mg) 3.5.32(H 2O) in this case the other elements are aluminium with sodium, calcium or magnesium, it also has water. Silicon dioxide forms more than 10 crystalline structures, quartz, tridymite, cristobalite. However, the proportion of silicon to oxygen is actually 1:2, hence the empirical formula SiO 2. The silicon atoms bond to the four oxygen atoms in a way which is also similar to carbon in diamond, a tetrahedral (triangular-based pyramid) structure. This is quite similar to diamond, although it alternates silicon (grey) with oxygen (red) instead of being all carbon atoms. Silicon dioxide is not really a molecule it forms a giant covalent structure with a crystalline arrangement like this (quartz): Wait a minute this is SiO 4 4- not SiO 2!Ī peculiarity of the silicon atom makes it preferable for it to bond to four oxygen atoms rather than two double bonds, as SiO 2 may suggest. Finally, its uses are abundant and varied we will see two of the main ones. Pure silica is usually found in the form of quartz (crystalline silica). It forms nearly two thirds of the Earth’s continental crust and it is still common further down in the mantle! Even more common are the silicate minerals, 90% of the crust (this includes all minerals which have silica and another element usually one which forms cations, for example magnesium) is made up of these silicates. It has a Mohs hardness of 7, being 10 the maximum (diamond). Silicon dioxide or silica is one of the hardest and most common materials in the Earth’s crust. This article is about silicon dioxide, a molecule which is not really a molecule, at least when it is found in nature, as it forms a giant covalent structure rather than a simple covalent structure. Silica The macromolecule that makes up sand, glass and quartz, and which is a major component of rocks and mountains. Silica - Molecule of the Month November 2013 - HTML-only version
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |