Question

Explain the difference in the structure of SiO2 and SiO4

Answer 1

In my opinion, the difference between a surface of amorphous silica and a stable surface of quartz (crystalline silica) is caused by the difference a number atoms on their surfaces. In the case of Si nanoparticles ratio of a number atoms on the surface to a number atoms in the volume increase with decrease of nanoparticles size. In this case a role of surface atoms in the determining of physical properties of nanoparticles increases.