Using the shorthand notation of Figure 22.9, draw the structure of the silicate anion in:
(a) K₄SiO₄ (b) Ag₁₀Si₄O₁₃
What is the relationship between the charge on the anion and the number of terminal O atoms?

Verified step by step guidance

1. Identify the silicate anion in each compound. For (a) K_4SiO_4, the silicate anion is SiO_4^{4-}. For (b) Ag_{10}Si_4O_{13}, the silicate anion is Si_4O_{13}^{10-}.
2. Determine the structure of the silicate anion. The SiO_4^{4-} anion is a tetrahedral structure with one silicon atom at the center and four oxygen atoms at the corners.
3. For Si_4O_{13}^{10-}, recognize that it is a combination of four SiO_4 tetrahedra sharing oxygen atoms. Identify the number of shared and terminal oxygen atoms.
4. Count the terminal oxygen atoms in each silicate anion. In SiO_4^{4-}, all four oxygen atoms are terminal. In Si_4O_{13}^{10-}, determine how many oxygen atoms are terminal by considering the shared oxygen atoms.
5. Relate the charge on the anion to the number of terminal oxygen atoms. Note that each terminal oxygen contributes a -1 charge, and shared oxygen atoms contribute less to the overall charge.

Key Concepts

Silicate Anions

Silicate anions are polyatomic ions composed of silicon and oxygen, typically represented in various structural forms. The basic unit is the silica tetrahedron (SiO4) where a silicon atom is surrounded by four oxygen atoms. These anions can combine in different ways to form larger structures, influencing their chemical properties and reactivity.

Coordination and Charge Balance

In silicate structures, the coordination of silicon and oxygen atoms determines the overall charge of the anion. Each terminal oxygen atom typically carries a negative charge, contributing to the anion's total charge. Understanding how these charges balance with cations in compounds like K4SiO4 and Ag10Si4O13 is crucial for predicting stability and reactivity.

Structural Representation

The shorthand notation for silicate structures simplifies the representation of complex silicate anions. This notation often uses symbols to denote silicon and oxygen atoms, along with lines to indicate bonds. Familiarity with this notation is essential for accurately drawing and interpreting the structures of silicate compounds, as well as understanding their relationships with cations.