Lewis structure of SiCl2Br2

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The Lewis structure of SiCl₂Br₂ contains four single bonds, with silicon in the center, and two chlorines and two bromines on either side. There are three lone pairs on each chlorine atom and each bromine 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 SiCl₂Br₂.

#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Calculate formal charge and check stability (if octet is already completed on central atom)

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 both chlorine and bromine are the group 17 elements. Hence, silicon has four valence electrons, and both chlorine and bromine have seven valence electrons.

Now SiCl₂Br₂ has one silicon atom, two chlorine atoms, and two bromine atoms.

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

Therefore, the total number of valence electrons = 4 + 14 + 14 = 32

• 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, chlorine, and bromine as follows:

Electronegativity value of silicon = 1.90
Electronegativity value of chlorine = 3.16
Electronegativity value of bromine = 2.96

Obviously, silicon is less electronegative than chlorine and bromine. Hence, assume that silicon is the central atom.

So now, put silicon in the center and chlorines and bromines on either side. And draw the rough skeleton structure for the Lewis structure of SiCl₂Br₂ something like this:

Also read: How to draw Lewis structure of POCl₃ (5 steps)

#2 Show chemical bond

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

Also read: How to draw Lewis structure of SOCl₂ (5 steps)

#3 Mark lone pairs

As calculated earlier, we have a total of 32 valence electrons. And in the above structure, we have already used eight valence electrons. Hence, twenty-four valence electrons are remaining.

Two valence electrons represent one lone pair. So twenty-four valence electrons = twelve lone pairs.

Note that both (silicon and chlorine) are the period 3 elements, so they can keep more than 8 electrons in their last shell. And bromine is a period 4 element, so it can 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 chlorines and bromines, so each chlorine and each bromine will get three lone pairs. And the central atom (silicon) will not get any lone pair, because all twelve lone pairs are used.

So the Lewis structure of SiCl₂Br₂ 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 ICl (5 steps)

#4 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 chlorine atom

Valence electrons = 7
Nonbonding electrons = 6
Bonding electrons = 2

Formal charge = 7 – 6 – ½ (2) = 0

• For each bromine atom

Valence electrons = 7
Nonbonding electrons = 6
Bonding electrons = 2

Formal charge = 7 – 6 – ½ (2) = 0

Mention the formal charges of atoms on the structure. So the Lewis structure of SiCl₂Br₂ looks something like this:

In the above structure, you can see that the formal charges of all atoms are zero. Therefore, this is the stable Lewis structure of SiCl₂Br₂.

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

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Related

• Lewis structure of POCl₃
• Lewis structure of SOCl₂
• Lewis structure of ICl
• Lewis structure of SO₂Cl₂
• Lewis structure of C₄H₁₀

External links

• SiCl2Br2 Lewis Structure in 6 Steps (With Images) – Pediabay
• How do you draw a Lewis Structure for SiCl2Br2? – Chegg
• Draw and explain the electron-dot diagram for SiCl2Br2 – Homework.Study.com
• SiCl2Br2 Lewis Structure, Geometry, Hybridization, and Polarity – Techiescientist
• sicl2br2 lewis structure – Brainly
• What is the Lewis structure for SiCl2Br2? – Answers