Lewis structure of SiO2

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The Lewis structure of SiO₂ contains two double bonds, with silicon in the center, and two oxygens on either side. There are two lone pairs on each oxygen atom, and the silicon atom does not have any lone pair.

Steps

By using the following steps, you can easily draw the Lewis structure of SiO₂:

#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Complete octet on central atom
#5 Calculate formal charge and check stability

Let’s one by one discuss each step in detail.

#1 Draw skeleton

In this step, first calculate the total number of valence electrons. And then, decide the central atom.

• Let’s calculate the total number of valence electrons

We know that… silicon is a group 14 element and oxygen is a group 16 element. Hence, silicon has four valence electrons and oxygen has six valence electrons.

Now SiO₂ has one silicon atom and two oxygen atoms.

So the total number of valence electrons = valence electrons of silicon atom + (valence electrons of oxygen atom × 2)

Therefore, the total number of valence electrons = 4 + 12 = 16

• Now decide the central atom

The atom with the least electronegative value is placed at the center. By looking at the periodic table, we get the electronegativity values for silicon and oxygen as follows:

Electronegativity value of silicon = 1.90
Electronegativity value of oxygen = 3.44

Obviously, silicon is less electronegative than oxygen. Hence, assume that silicon is the central atom.

So now, put silicon in the center and oxygens on either side. And draw the rough skeleton structure for the Lewis structure of SiO₂ something like this:

Also read: How to draw Lewis structure of ethanol (4 steps)

#2 Show chemical bond

Place two electrons between the atoms to show a chemical bond. Since silicon is surrounded by two oxygens, use four electrons to show two chemical bonds as follows:

#3 Mark lone pairs

As calculated earlier, we have a total of 16 valence electrons. And in the above structure, we have already used four valence electrons. Hence, twelve valence electrons are remaining.

Two valence electrons represent one lone pair. So twelve valence electrons = six lone pairs.

Note that silicon is period 3 element, so it can keep more than 8 electrons in its last shell. And oxygen is a period 2 element, so it can not keep more than 8 electrons in its last shell.

Also, make sure that you start marking these lone pairs on outside atoms first. And then, on the central atom.

The outside atoms are oxygens, so each oxygen will get three lone pairs. And the central atom (silicon) will not get any lone pair, because all six lone pairs are used.

So the Lewis structure of SiO₂ looks something like this:

In the above structure, you can see that the octet is completed on outside atoms. But, the central atom (silicon) doesn’t form an octet.

So in the next step, we have to complete the octet on the central atom.

Also read: How to draw Lewis structure of N₂H₄ (4 steps)

#4 Complete octet on central atom

Remember that silicon is a period 3 element, so it can keep more than 8 electrons in its last shell.

Now silicon already has four valence electrons. Hence, silicon needs four more valence electrons to complete its octet.

So convert one lone pair from each oxygen atom to make a new bond with the silicon atom. And then, the Lewis structure of SiO₂ looks something like this:

In the above structure, you can see that the octet is completed on the central atom (silicon), and also on the outside atoms. Therefore, the octet rule is satisfied.

After completing the octet, one last thing we need to do is, calculate the formal charge and check the stability of the above structure.

Also read: How to draw Lewis structure of HBr (4 steps)

#5 Calculate formal charge and check stability

The following formula is used to calculate the formal charges on atoms:

Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons

Collect the data from the above structure and then, write it down below as follows:

• For silicon atom

Valence electrons = 4
Nonbonding electrons = 0
Bonding electrons = 8

Formal charge = 4 – 0 – ½ (8) = 0

• For each oxygen atom

Valence electrons = 6
Nonbonding electrons = 4
Bonding electrons = 4

Formal charge = 6 – 4 – ½ (4) = 0

Mention the formal charges of atoms on the structure. So the Lewis structure of SiO₂ looks something like this:

In the above structure, you can see that the formal charges of both (silicon and oxygen) are zero. Therefore, this is the stable Lewis structure of SiO₂.

And each horizontal line drawn in the above structure represents a pair of bonding valence electrons.

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Related

• Lewis structure of ethanol
• Lewis structure of N₂H₄
• Lewis structure of HBr
• Lewis structure of H₂SO₄
• Lewis structure of OH^–

External links

• SiO2 lewis structure, molecular geometry, bond angle, polarity, electrons – Topblogtenz
• SiO2 Lewis Structure, Molecular Geometry, Hybridization, and Polarity – Techiescientist
• SiO2 Lewis Structure| Step By Step Construction – What’s Insight
• SiO2 Lewis Structure in 6 Steps (With Images) – Pediabay
• Chemical Bonding: SiO2 Lewis Structure – The Geoexchange
• Construct the Lewis structure for the covalent compound silicon dioxide (SiO2) – Homework.Study.com
• Construct the Lewis structure for the covalent compound silicon dioxide (SiO2) – Chegg
• What is Lewis structure of SiO2? – Answers
• Draw the lewis structure for sio2 and indicate how many unshared pairs of electron are present on the silicon? – Brainly
• SiO2 Lewis Structure Electron geometry Valence electrons Molecular geometry – Bartleby
• What is the structure and bonding in SiO2 – ResearchGate
• Silicon Oxide Lewis Dot Structure | Science – ShowMe
• SiO2 Polar or Nonpolar – Laurence Lavelle
• File:SiO2 Molecule.png – Wikimedia Commons