It is an acid anhydride of acidic oxides and silicic acid. The chemical properties are very stable. Insoluble in water, does not react with water, and does not react with ordinary acids. Can react with hydrogen fluoride gas or hydrofluoric acid to generate silicon tetrafluoride gas.

It has other properties of acidic oxides and can react with bases (strong alkaline solutions or melted bases) at high temperatures to form salts and water.

At room temperature, strong alkaline solutions slowly react with SiO2 to form corresponding silicates. Strong alkaline solution can corrode glass, so glass bottles storing strong alkaline solution cannot use ground glass stoppers. If glass stoppers (containing SiO2 in glass) are used, sticky sodium silicate will be generated, which will bond the glass stopper and bottle mouth together. Concentrated alkali solution cannot be stored in glass bottles for a long time.

Silicon dioxide and alkaline oxides or carbonates of certain metals melt together at high temperatures to form silicates.

By cooling the molten sodium silicate at this high temperature, quartz glass can be obtained, which has good UV transmittance and can be used as mercury lampshades, high-temperature resistant chemical instruments, quartz crucibles, and optical instruments.