Silicon dioxide is an inorganic substance. Silicon atoms and oxygen atoms are arranged in long-range order to form crystalline silicon dioxide, and short-range order or long-range disorder to form amorphous silicon dioxide.
In silicon dioxide crystal, silicon atom is located at the center of the regular tetrahedron, and four oxygen atoms are located at the four top corners of the regular tetrahedron. Many such tetrahedrons are connected through the oxygen atoms at the top corners. Each oxygen atom is shared by two tetrahedrons, that is, each oxygen atom is combined with two silicon protons.
The chemical properties of silica are relatively stable. It doesn't react with water. It is an acidic oxide and does not react with general acids. Hydrofluoric acid reacts with silica to form gaseous silicon tetrafluoride. React with hot concentrated alkali solution or molten alkali to form silicate and water. It reacts with a variety of metal oxides at high temperature to form silicate. Silica is inactive in nature. It does not interact with halogen, hydrogen halide, sulfuric acid, nitric acid and perchloric acid other than fluorine and hydrogen fluoride.
When silica crystallizes perfectly, it is crystal; Silica gelled and dehydrated is agate; Silica colloid containing water becomes opal after solidification; When the grain size of silica is less than a few microns, it forms chalcedony, chert and secondary quartzite. It is a mineral resource with very stable physical and chemical properties. The crystal belongs to the oxide mineral of cubic system, that is, low-temperature quartz. It is the most widely distributed mineral in the quartz family.