(a) What is the characteristic geometry about silicon in all silicate minerals? (b) Metasilicic acid has the empirical formula \(\mathrm{H}_{2} \mathrm{SiO}_{3} .\) Which of the structures shown in Figure 22.32 would you expect metasilicic acid to have?

To understand the characteristic geometry of silicon in silicate minerals, we need to look at the composition and formation of silicates in general. The silicon-oxygen tetrahedron, [SiO4]^4-, is the basic building block of silicate minerals. It consists of a central silicon atom, which is coordinated to four surrounding oxygen atoms in the form of a tetrahedron. This is the characteristic geometry of silicon in silicate minerals. Now, let's move on to part (b) of the exercise.

Metasilicic acid has an empirical formula of H2SiO3. This means it has one silicon atom, two hydrogen atoms, and three oxygen atoms in each formula unit. We are asked to determine which of the structures shown in Figure 22.32 would best represent metasilicic acid. Unfortunately, we do not have access to Figure 22.32, but we can describe an appropriate structure based on the empirical formula. Since metasilicic acid has only one SiO4 tetrahedron due to its single silicon atom, it is reasonable to assume that one of the four oxygens in the SiO4 tetrahedron is protonated with a hydrogen atom (so it becomes a hydroxyl group, OH). This leaves three remaining oxygen atoms in the SiO4 tetrahedron, which corresponds to the structure of metasilicic acid, H2SiO3. In conclusion: 1. The characteristic geometry of silicon in all silicate minerals is a tetrahedron, formed by the silicon-oxygen tetrahedron [SiO4]^4-. 2. Based on the empirical formula H2SiO3, metasilicic acid is expected to have a structure with a single SiO4 tetrahedron, where one of the oxygen atoms is protonated with a hydrogen atom to form a hydroxyl group (OH).