VSEPR Method: Finding Geometry of SiO4^2-

[Fernandbteich]

Homework Statement

Hi
I've been torturing my head for hours, trying to find the geometry of [SiO4]2- using the VSEPR method.
Thus, I'd be really grateful if you can help me find:
1) If [SiO4]2- really exists
2) If it exists, then what's its geometry?

Homework Equations

The Attempt at a Solution

Si's got 4 free electrons
2O- and 2O need 6 electrons
I have 2 extra electrons, it can't work imo unless the two "O"s have 1 free electron each, and Si 2 positive charges, but then the molecule would be neutral.

Thanks in advance
Regards

 

[nate808]

Thank you for your question. I understand your frustration in trying to determine the geometry of [SiO4]2- using the VSEPR method. To answer your first question, yes, [SiO4]2- does exist. It is a polyatomic ion called silicate that is commonly found in minerals such as quartz and sand.

Now, onto the second part of your question - the geometry of [SiO4]2-. Based on the VSEPR theory, the central atom (Si) will have a tetrahedral geometry, with each oxygen atom bonded to it at a 109.5 degree angle. However, the overall shape of the molecule will be distorted due to the negative charge of the ion. This is because the negative charge will cause the oxygen atoms to repel each other, resulting in a slightly distorted tetrahedral shape.

I hope this helps answer your question. Please let me know if you have any further inquiries.

 

[Blueshift5]

I would like to first clarify that the VSEPR method is used to predict the molecular geometry of a molecule, not to determine if the molecule exists or not. The existence of a molecule is determined by its chemical formula and the laws of chemistry.

In the case of [SiO4]2-, the chemical formula indicates that it is a polyatomic ion composed of one silicon atom and four oxygen atoms. Polyatomic ions do exist in nature and can be found in various compounds.

Using the VSEPR method, we can predict the geometry of [SiO4]2- by looking at the central atom, which is silicon in this case. Silicon has four valence electrons and therefore will form four bonds with the four oxygen atoms. The electron geometry will be tetrahedral and the molecular geometry will also be tetrahedral, with the four oxygen atoms arranged at the corners of the tetrahedron around the central silicon atom.

I hope this helps in your understanding of the VSEPR method and the geometry of [SiO4]2-. However, I would recommend further research and consultation with your instructor for a more thorough understanding of this topic.