Lewis Structure of SiS2 (With 6 Simple Steps to Draw!)

Lewis Structure of SiS2

I’m super excited to teach you the lewis structure of SiS2 in just 6 simple steps.

Infact, I’ve also given the step-by-step images for drawing the lewis dot structure of SiS2 molecule.

So, if you are ready to go with these 6 simple steps, then let’s dive right into it!

Lewis structure of SiS2 contains two double bonds between the Silicon (Si) atom and each Sulfur (S) atom. The Silicon atom (Si) is at the center and it is surrounded by 2 Sulfur atoms (S). The Silicon atom does not have a lone pair while both the Sulfur atoms have 2 lone pairs.

Let’s draw and understand this lewis dot structure step by step.

(Note: Take a pen and paper with you and try to draw this lewis structure along with me. I am sure you will definitely learn how to draw lewis structure of SiS2).

6 Steps to Draw the Lewis Structure of SiS2

Step #1: Calculate the total number of valence electrons

Here, the given molecule is SiS2. In order to draw the lewis structure of SiS2, first of all you have to find the total number of valence electrons present in the SiS2 molecule.
(Valence electrons are the number of electrons present in the outermost shell of an atom).

So, let’s calculate this first.

Calculation of valence electrons in SiS2

  • For Silicon: 

Silicon is a group 14 element on the periodic table.

Hence, the valence electrons present in silicon is 4 (see below image).

  • For Sulfur:

Sulfur is a group 16 element on the periodic table.

Hence, the valence electrons present in sulfur is 6 (see below image).

Hence in a SiS2 molecule, 

Valence electrons given by Silicon (Si) atom = 4
Valence electrons given by each Sulfur (S) atom = 6
So, total number of Valence electrons in SiS2 molecule = 4 + 6(2) = 16

Step #2: Select the center atom

While selecting the atom, always put the least electronegative atom at the center. 

(Remember: Fluorine is the most electronegative element on the periodic table and the electronegativity decreases as we move right to left in the periodic table as well as top to bottom in the periodic table).

Here in the SiS2 molecule, if we compare the silicon atom (Si) and sulfur atom (S), then the silicon is less electronegative than sulfur.

So, silicon should be placed in the center and the remaining 2 sulfur atoms will surround it.

step 1

Step #3: Put two electrons between the atoms to represent a chemical bond

Now in the above sketch of SiS2 molecule, put the two electrons (i.e electron pair) between each silicon atom and sulfur atom to represent a chemical bond between them.

step 2

These pairs of electrons present between the Silicon (Si) and Sulfur (S) atoms form a chemical bond, which bonds the silicon and sulfur atoms with each other in a SiS2 molecule.

Step #4: Complete the octet (or duplet) on outside atoms. If the valence electrons are left, then put the valence electrons pair on the central atom

Don’t worry, I’ll explain!

In the Lewis structure of SiS2, the outer atoms are sulfur atoms.

So now, you have to complete the octet on these sulfur atoms (because sulfur requires 8 electrons to have a complete outer shell).

step 3

Now, you can see in the above image that all the sulfur atoms form an octet.

Also, all the 16 valence electrons of SiS2 molecule (as calculated in step #1) are used in the above structure. So there are no remaining electron pairs.

Hence there is no change in the above sketch of SiS2.

Let’s move to the next step.

Step #5: Check whether the central atom has octet or not. If it does not have an octet, then move the electron pair from the outer atom to form a double bond or triple bond

In this step, we have to check whether the central atom (i.e silicon) has an octet or not. 

In simple words, we have to check whether the central Silicon (Si) atom is having 8 electrons or not.

step 4

As you can see from the above image, the central atom (i.e silicon) has only 4 electrons. So it does not fulfill the octet rule.

Now, in order to fulfill the octet of a silicon atom, we have to move the electron pair from the outer atom (i.e sulfur atom) to form a double bond.

step 5

Still, the octet of silicon atom is not fulfilled as it has only 6 electrons.

So again moving the electron pair from another sulfur atom, we will get the following structure.

step 6

Now you can see from the above image that the central atom (i.e silicon), is having 8 electrons. So it fulfills the octet rule and the silicon atom is stable.

Step #6: Final step – Check the stability of lewis structure by calculating the formal charge on each atom

Now, you have come to the final step and here you have to check the formal charge on silicon atom (Si) as well as each sulfur atom (S).

For that, you need to remember the formula of formal charge;

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

step 7
  • For Silicon:
    Valence electrons = 4 (as it is in group 14)
    Nonbonding electrons = 0
    Bonding electrons = 8
  • For Sulfur:
    Valence electrons = 6 (as it is in group 16)
    Nonbonding electrons = 4
    Bonding electrons = 4
Formal charge=Valence electronsNonbonding electrons(Bonding electrons)/2
Si=408/2=0
S=644/2=0

So you can see above that the formal charges on silicon as well as sulfur are “zero”.

Hence, there will not be any change in the above structure and the above lewis structure of SiS2 is the final stable structure only.

Each electron pair (:) in the lewis dot structure of SiS2 represents the single bond ( | ). So the above lewis dot structure of SiS2 can also be represented as shown below.

SiS2 Lewis structure

Related lewis structures for your practice:
Lewis Structure of OCS
Lewis Structure of Br3-
Lewis Structure of H3O+
Lewis Structure of CH3NO2
Lewis Structure of AsH3 

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