Silicon dioxide does not react with acid. Long range ordered arrangement of silicon and oxygen atoms forms crystalline silicon dioxide, while short-range ordered or long-range disordered arrangement forms amorphous silicon dioxide. In silicon dioxide crystals, silicon atoms are located at the center of a regular tetrahedron, and four oxygen atoms are located at the four vertices of the regular tetrahedron. Many of these tetrahedra are connected by oxygen atoms at the vertices, and each oxygen atom is shared by two tetrahedra, meaning that each oxygen atom is combined with two silicon atoms.
Acid in chemistry refers to compounds that produce hydrogen ions as cations when ionized in aqueous solution, and can be divided into inorganic acids and organic acids. The acid-base proton theory holds that substances that can release protons are collectively referred to as acids. The Lewis acid-base theory holds that electrophilic reagents or electron acceptors are Lewis acids.