Lewis Structure of SiCl2Br2 (With 6 Simple Steps to Draw!)

Ready to learn how to draw the lewis structure of SiCl2Br2?

Awesome!

Here, I have explained 6 simple steps to draw the lewis dot structure of SiCl2Br2 (along with images).

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

Lewis structure of SiCl2Br2 contains a single bond between the Silicon-Chlorine atoms and Silicon-Bromine atoms. The Silicon atom (Si) is at the center and it is surrounded by 2 Chlorine atoms (Cl) and 2 Bromine atoms (Br). The Silicon atom does not have a lone pair while the chlorine & bromine atoms have three lone pairs each.

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 SiCl2Br2).

6 Steps to Draw the Lewis Structure of SiCl2Br2

Step #1: Calculate the total number of valence electrons

Here, the given molecule is SiCl2Br2. In order to draw the lewis structure of SiCl2Br2, first of all you have to find the total number of valence electrons present in the SiCl2Br2 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 SiCl2Br2

• For Silicon: 

Silicon is a group 14 element on the periodic table. ^[1]

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

• For Chlorine:

Chlorine is a group 17 element on the periodic table. ^[2]

Hence, the valence electron present in chlorine is 7 (see below image).

• For Bromine:

Bromine is a group 17 element on the periodic table. ^[3]

Hence, the valence electrons present in bromine is 7 (see below image).

Hence in a SiCl2Br2 molecule, 

Valence electrons given by Silicon (Si) atom = 4
Valence electrons given by each Chlorine (Cl) atom = 7 
Valence electrons given by each Bromine (Br) atom = 7
So, total number of Valence electrons in SiCl2Br2 molecule = 4 + 7(2) + 7(2) = 32

Step #2: Select the center atom

While selecting the center 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). ^[4]

Here in the SiCl2Br2 molecule, if we compare the silicon atom (Si), chlorine atom (Cl) and bromine atom (Br), then silicon is less electronegative.

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

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

Now in the above sketch of SiCl2Br2 molecule, put the two electrons (i.e electron pair) between each silicon-chlorine and silicon-bromine atoms to represent a chemical bond between them.

These pairs of electrons present between the Silicon (Si), Chlorine (Cl) and Bromine (Br) atoms form a chemical bond, which bonds these atoms in a SiCl2Br2 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 SiCl2Br2, the outer atoms are chlorine atoms and bromine atoms.

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

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

Also, all the 32 valence electrons of SiCl2Br2 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 SiCl2Br2.

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.

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

Step #6: 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), chlorine atoms (Cl) as well as bromine atoms (Br).

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

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

• For Silicon:
  Valence electrons = 4 (as it is in group 14)
  Nonbonding electrons = 0
  Bonding electrons = 8

• For Chlorine:
  Valence electron = 7 (as it is in group 17)
  Nonbonding electrons = 6
  Bonding electrons = 2

• For Bromine:
  Valence electron = 7 (as it is in group 17)
  Nonbonding electrons = 6
  Bonding electrons = 2

Formal charge	=	Valence electrons	–	Nonbonding electrons	–	(Bonding electrons)/2
Si	=	4	–	0	–	8/2	=	0
Cl	=	7	–	6	–	2/2	=	0
Br	=	7	–	6	–	2/2	=	0

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

Hence, there will not be any change in the above structure and the above lewis structure of SiCl2Br2 is the final stable structure only.

Each electron pair (:) in the lewis dot structure of SiCl2Br2 represents the single bond ( | ). So the above lewis dot structure of SiCl2Br2 can also be represented as shown below.

Related lewis structures for your practice:
Lewis Structure of SbF5
Lewis Structure of ClBr3
Lewis Structure of GeH4
Lewis Structure of FCN
Lewis Structure of HClO2 

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