SiO2 Lewis Structure in 6 Steps (With Images)

So you have seen the above image by now, right?

Let me explain the above image in short.

SiO2 lewis structure has a Silicon atom (Si) at the center which is surrounded by two Oxygen atoms (O). There are 2 double bonds between the Silicon atom (Si) and each Oxygen atom (O). There are 2 lone pairs on both the Oxygen atoms (O).

If you haven’t understood anything from the above image of SiO2 (silicon dioxide) lewis structure, then just stick with me and you will get the detailed step by step explanation on drawing a lewis structure of SiO2.

So let’s move to the steps of drawing the lewis structure of SiO2.

Steps of drawing SiO2 lewis structure

Step 1: Find the total valence electrons in SiO2 molecule

In order to find the total valence electrons in a SiO2 (silicon dioxide) molecule, first of all you should know the valence electrons present in silicon atom as well as oxygen atom.
(Valence electrons are the electrons that are present in the outermost orbit of any atom.)

Here, I’ll tell you how you can easily find the valence electrons of silicon as well as oxygen using a periodic table.

Total valence electrons in SiO2 molecule

→ Valence electrons given by silicon atom:

Silicon is a group 14 element on the periodic table. ^[1] Hence the valence electrons present in silicon is 4.

You can see the 4 valence electrons present in the silicon atom as shown in the above image.

→ Valence electrons given by oxygen atom:

Oxygen is group 16 element on the periodic table. ^[2] Hence the valence electrons present in oxygen is 6.

You can see the 6 valence electrons present in the oxygen atom as shown in the above image.

Hence, 

Total valence electrons in SiO2 molecule = valence electrons given by 1 silicon atom + valence electrons given by 2 oxygen atoms = 4 + 6(2) = 16.

Step 2: Select the central atom

For selecting the center atom, you have to remember that the atom which is less electronegative remains at the center.

Now here the given molecule is SiO2 (silicon dioxide) and it contains silicon atom (Si) and oxygen atoms (O).

You can see the electronegativity values of silicon atom (Si) and oxygen atom (O) in the above periodic table.

If we compare the electronegativity values of silicon (Si) and oxygen (O) then the silicon atom is less electronegative.

So here the silicon atom (Si) is the center atom and the oxygen atoms (O) are the outside atoms.

Step 3: Connect each atoms by putting an electron pair between them

Now in the SiO2 molecule, you have to put the electron pairs between the silicon atom (Si) and oxygen atoms (O).

This indicates that the silicon (Si) and oxygen (O) are chemically bonded with each other in a SiO2 molecule.

Step 4: Make the outer atoms stable

Now in this step, you have to check the stability of the outer atoms.

Here in the sketch of SiO2 molecule, you can see that the outer atoms are oxygen atoms.

These outer oxygen atoms are forming an octet and hence they are stable. 

Also, in step 1 we have calculated the total number of valence electrons present in the SiO2 molecule.

The SiO2 molecule has a total 16 valence electrons and all these valence electrons are used in the above sketch of SiO2.

Hence there are no remaining electron pairs to be kept on the central atom. 

So now let’s proceed to the next step.

Step 5: Check the octet on the central atom. If it does not have octet, then shift the lone pair to form a double bond or triple bond.

In this step, you have to check whether the central silicon atom (Si) is stable or not.

In order to check the stability of the central silicon (Si) atom, we have to check whether it is forming an octet or not.

Unfortunately, the silicon atom is not forming an octet here. Silicon has only 4 electrons and it is unstable.

Now to make this silicon atom stable, you have to shift the electron pair from the outer oxygen atom so that the silicon atom can have 8 electrons (i.e octet).

But after shifting one electron pair, the silicon atom is still not forming an octet as it has only 6 electrons. 

So again we have to shift one more electron pair from the other oxygen atom.

After shifting this electron pair, the central silicon atom will get 2 more electrons and thus its total electrons will become 8.

You can see from the above picture that the silicon atom is forming an octet.

And hence the silicon atom is stable.

Now let’s proceed to the final step to check whether the lewis structure of SiO2 is stable or not.

Step 6: Check the stability of lewis structure

Now you have come to the final step in which you have to check the stability of lewis structure of SiO2.

The stability of lewis structure can be checked by using a concept of formal charge.

In short, now you have to find the formal charge on silicon (Si) atom as well as oxygen (O) atoms present in the SiO2 molecule.

For calculating the formal charge, you have to use the following formula;

Formal charge = Valence electrons – (Bonding electrons)/2 – Nonbonding electrons

You can see the number of bonding electrons and nonbonding electrons for each atom of SiO2 molecule in the image given below.

For Silicon (Si) atom:
Valence electrons = 4 (because silicon is in group 14)
Bonding electrons = 8
Nonbonding electrons = 0

For Oxygen (O) atom:
Valence electrons = 6 (because oxygen is in group 16)
Bonding electrons = 4
Nonbonding electrons = 4

Formal charge	=	Valence electrons	–	(Bonding electrons)/2	–	Nonbonding electrons
Si	=	4	–	8/2	–	0	=	0
O	=	6	–	4/2	–	4	=	0

From the above calculations of formal charge, you can see that the silicon (Si) atom as well as oxygen (O) atom has a “zero” formal charge.

This indicates that the above lewis structure of SiO2 is stable and there is no further change in the above structure of SiO2.

In the above lewis dot structure of SiO2, you can also represent each bonding electron pair (:) as a single bond (|). By doing so, you will get the following lewis structure of SiO2.

I hope you have completely understood all the above steps.

For more practice and better understanding, you can try other lewis structures listed below.

Try (or at least See) these lewis structures for better understanding:

SiH4 lewis structure	ClO4- lewis structure
ClO- lewis structure	NOCl lewis structure
SeO2 lewis structure	OCl2 lewis structure