# Polarity, Lewis Structure, Molecular Geometry, and Hybridization of SiO2

Silicon dioxide, usually referred to as silica, is a chemical substance with the formula SiO2. It is composed of one atom of silicon and two atoms of oxygen. It is predominantly found in sand.

In this article, we will examine the Lewis structure of silicon dioxide (SiO2), as well as its molecular geometry, polarity, hybridization, and bond angle.

## Silicon Dioxide (SiO2) Lewis Structure

SiO2’s Lewis structure is identical to that of carbon dioxide. The only difference is that silicon is utilised in place of carbon.

One silicon atom is in the centre, with two oxygen atoms double-bonded to it. Lewis dot structure of SiO2 lacks lone pairs on the core atom.

Let’s examine how to accomplish this step by step.

Step 1: Determine the total number of valence electrons present in SiO2.

Determine how many valence electrons SiO2 has as the first stage. Since silicon is in the 14th group and oxygen is in the 16th group of the periodic table, silicon has four valence electrons while oxygen has six.

Electronic configuration of oxygen = 1s2 2s2 2p4

Electronic arrangement of silicon = 1s2 2s2 2p6 3s2 3p2

Thus, the number of valence electrons in oxygen is six

Four valence electrons make up Silicon

In the Lewis structure of SiO2, the total number of accessible valence electrons is 4 + 2*6 = 16 electrons.

Step 2: Identify the atom with the lowest electronegativity and place it in the centre.

We will search for the atom between silicon and oxygen with the least electronegative charge and place it in the middle of the SiO2 Lewis structure.

As electronegativity rises from left to right in the periodic table, we discovered that silicon is less electronegative than oxygen.

Place silicon in the centre, and evenly space oxygen around it.

Connect all oxygen atoms to the silicon atom via a single connection in step three.

Because a single bond comprises two electrons, we utilised two single bonds in the construction. It indicates that four of a total of 16 valence electrons were utilised.

Position the remaining valence electrons, commencing with the outermost atom.

Now, there are twelve additional valence electrons.

Place the lone remaining valence electron first around the outermost atom (oxygen). To complete the octet, we need 12 extra valence electrons, and oxygen requires 8 electrons.

Nonetheless, oxygen shares two electrons via a single link. Add six additional electrons to each oxygen atom.

We have placed six of the remaining twelve valence electrons around each oxygen atom.

However, this structure is not yet stable because silicon is surrounded by only four electrons and needs four more to complete its octet.

Let’s complete it in the subsequent phase.

Complete the octet of the centre atom, and if possible, make a covalent link.

This is the final step in constructing the SiO2 Lewis diagram. As we all know, silicon requires eight electrons to complete its octet, but it now contains only four.

By converting the electrons of an oxygen atom into a covalent link, we could create an octet of silicon.

As depicted by the Lewis dot structure of SiO2, we convert two unpaired electrons from each oxygen atom into covalent bonds. As a result, both silicon and oxygen have eight electrons in their valence shells.

## Molecular Geometry and Hybridization of SiO2.

SiO2’s molecular geometry can be determined using the VSEPR theory. Let’s examine the procedure for doing so.

Follow these methods to discover the molecular geometry of SiO2.

Determine SiO2 hybridization.

What does SiO2 hybridization entail? We must first determine its quantity of hybridization. There exists a formula for this.

Hybridization Number = Number of atoms attached to the core atom plus the number of lone pairs on that atom.

Silicon is the fundamental element. It has two atoms linked to it, but no lone pairs.

Number of hybridization = 2 plus 0 = 2

This indicates that SiO2 hybridization is Sp.

In the Lewis structure of SiO2, determine the number of bond pairs and lone pairs.

There are no lone electron pairs on the core atom in the Lewis structure of silicon dioxide. Additionally, there are two bond pairings between oxygen and silicon and silicon and oxygen.

There are thus no lone pairings and two bond pairs.

According to the VSEPR theory, a molecule’s molecular and electron geometry is linear if it possesses Sp hybridization, two bond pairs, and no lone pair on the central atom.

Permit me to briefly describe the VSEPR Theory.

## The Theory of

The VSEPR theory of Sidgwick and Powell gives a fundamental mechanism for predicting the shape of covalent molecules. This idea is based on the repulsive interactions between the valance electrons of atoms.

Due to electron repulsion, bond pairs find a position in space that minimises repulsive interactions and increases the distance between them. Lone pairs are non-bonded valence electrons with a greater level of repulsion than bond pairs.

Let’s examine the VSEPR chart to determine how it operates.

AX2 is the generic formula for the molecular geometry of SiO2 according to the above chart.

The bond angle is 180 degrees since there is no lone pair on the centre atom of SiO2 in the Lewis dot diagram. Since there is no repulsion between the lone and bond pair, there is no effect on the bond angle.

The geometry around an atom with only two bonds and no unshared electrons is a straight line, according to the VSEPR theory.

## Polar or non-polar, is SiO2?

Since the net dipole moment is zero, it is evident that SiO2 is non-polar. The majority of molecules with Sp hybridization and linear molecular geometry are non-polar due to the fact that the dipole moment created along with the bond is easily cancelled.

The Si-O bond on both sides of SiO2 is symmetrically organised, which cancels out the dipole because both sides have the same magnitude.

Listed below are the variables that impact polarity:

## Electronegativity

The bigger the difference between atoms’ electronegativity, the stronger their polarity. Silicon has an electronegativity of around 1.95, whereas oxygen’s is 3.45.

Difference in electronegativity = 3.45 – 1.95 = 1.5

The Si-O bond is polar due to the difference in electronegativity between silicon and oxygen. Due to its symmetric shape, however, the molecule as a whole is nonpolar.

## Dipole Moment

Due to the formation of two dipole moments in opposite directions between silicon and oxygen, the net dipole moment of SiO2 is zero.

As there is a uniform charge distribution and the configuration is symmetrical, dipoles cancel each other out.

Dipole moment Equals atomic charge multiplied by atomic distance.

## Molecular Geometry

We are aware that the molecular structure of SiO2 is linear and very symmetrical. In addition, the Lewis structure of silicon dioxide contains no lone electron pairs.

Since there is no shape distortion, it is straightforward to cancel out the dipole moment caused by the Si-O bond.

SiO2 is a non-polar molecule as a result of these features.

## Silicon Dioxide Uses

Silicon dioxide has a wide variety of uses. Several of them are provided below.

Silicon dioxide is utilised as a tranquillizer.

It has applications as a flavour enhancer in the food business.

It is used to reduce the stickiness of powdered substances.

It is used as a de-clumping agent.

It is utilised in the production of cement and concrete.

## Conclusion

SiO2 has zero net dipole moment. It possesses a linear electron and molecular geometry, a 180-degree bond angle, and a Sp hybridization. The Lewis structure of silicon dioxide contains a total of 16 valence electrons. The formal charge in the Lewis dot structure of SiO2 is zero.

Happy Learning.

Read more: Polar or nonpolar is PCl3?

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.