In these structures each silicon has two bridging and two terminal oxygen atoms, and the charge density is -2 per silicon atom. These structures are sometimes called metasilicates and can be classified as cyclosilicates . 2- units link together into long chains. In these structures each silicon has 2 terminal oxygens and 2 bridging oxygens. The charge density is -2 per silicon atom.
Single chain polysilicates comprise part of the subclass inosilicates .
These double chain structures are also classified as inosilicates . A polysilicate sheet looks a bit like a sheet of chicken wire composed of a hexagonal network. These sheet polysilicates are classified as phyllosilicates . In these sheets each silicon possesses 1 terminal oxygen and 3 bridging oxygens. The charge density per silicon is -1.