In group 16 silicon dioxide is often a very common compound that greatly happens as sand or quartz. SiO2 is tetrahedral with each silicon atom surrounded by 4 oxygen atoms. Quite a few crystalline sorts exist Using the tetrahedra linked to type a polymeric chain. Examples are tridymite and cristobalite. https://3dprinterfilament04703.pointblog.net/detailed-notes-on-hollow-glass-sphere-87679684