Using the shorthand notation of Figure 22.9, draw the structure of the silicate anion in: (a) K 4 SiO 4 (b) Ag 10 Si 4 O 13 What is the relationship between the charge on the anion and the number of terminal O atoms?

Hi, everyone. Let's take a look at our next question. What is the tetrahedron based shorthand notation for the silicone anion silicate anion in N A nine si 3010? What is the relationship between the number of terminal O atoms and the charge of an anion? Let's think about how we draw these tetrahedron based shorthand structures. We know that each unit that makes a tetrahedron. So each unit, so each of these little pyramids consists of one silicon atom that's at the center of our tetrahedron and an oxygen at each corner. So each corner represents an oxygen atom of which the unshared oxygen. So unshared Warners have a charge of negative one and the shared oxygens have a charge of zero because they are bonded to two silicon atoms. So when we talk about the number of terminal oxygen atoms and the charge of an anion, well, a terminal oxygen atom would be unshared. So therefore the number of terminal oxygen atoms will equal the am I charge since each one has a negative one charge. So that's one part of our answer. So I'll highlight it here that the number of terminal or unshared oxygen atoms equals the charge of the anion. So with that in mind, we can figure out what our tetrahedral structure should look like because we have these nine sodiums in our chemical formula, each of the sodiums of course, will have a charge of plus one being those group, one, a metal atoms. So that will mean we have a plus nine charged from all our sodiums. And so are si units there si O units must have a charge of negative nine. So we know we must have nine unshared oxygen atoms due to that negative nine charge. And since we have a total of 10 oxygen atoms, we must have one shared oxygen. And that means only one corner can be shared among our three pyramids. So let's draw a structure where we have three parameter units with just one shared oxygen. So I now have a structure with three tetrahedrons that meet in the middle touching at 1.1 corner. So that would represent our one shared oxygen that has these bonds and nine unshared corners representing the other nine oxygen atoms and correctly demonstrating the charge of negative nine on the anion. So there's our parameter structure. And of course, as we said, the number of terminal oxygen atoms will equal the charge of the anion. See you in the next video.

Ch.22 - The Main Group Elements

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McMurry 8th Edition

Ch.22 - The Main Group Elements

Problem 22.99

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Chapter 22, Problem 22.99

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?

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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-}.

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.

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.

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.

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.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

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.