SiCl2Br2 Lewis structure

SiCl₂Br₂ (dibromo dichlorosilane) has one silicon atom, two chlorine atoms, and two bromine atoms.

In the SiCl₂Br₂ Lewis structure, there are four single bonds around the silicon atom, with two chlorine atoms and two bromine atoms attached to it, and on each chlorine and bromine atom, there are three lone pairs.

Alternative method: Lewis structure of SiCl₂Br₂

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, silicon lies in group 14, and both chlorine and bromine lie in group 17.

Hence, silicon has four valence electrons, both chlorine and bromine have seven valence electrons.

Since SiCl₂Br₂ has one silicon atom, two chlorine atoms, and two bromine atoms, so…

Valence electrons of one silicon atom = 4 × 1 = 4
Valence electrons of two chlorine atoms = 7 × 2 = 14
Valence electrons of two bromine atoms = 7 × 2 = 14

And the total valence electrons = 4 + 14 + 14 = 32

Learn how to find: Silicon valence electrons, Chlorine valence electrons, and Bromine valence electrons

• Second, find the total electron pairs

We have a total of 32 valence electrons. And when we divide this value by two, we get the value of total electron pairs.

Total electron pairs = total valence electrons ÷ 2

So the total electron pairs = 32 ÷ 2 = 16

• Third, determine the central atom

We have to place the least electronegative atom at the center.

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

Therefore, place silicon in the center and chlorine and bromine on either side.

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 16 electron pairs. And four bonds are already marked. So we have to only mark the remaining twelve electron pairs as lone pairs on the sketch.

Also remember 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.

Always start to mark the lone pairs from outside atoms. Here, the outside atoms are chlorines and bromines.

So for each chlorine and bromine, there are three lone pairs, and for silicon, there is zero lone pair because all twelve electron pairs are over.

Mark the lone pairs on the sketch as follows:

Formal charge

Use the following formula to calculate the formal charges on atoms:

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

For silicon atom, formal charge = 4 – 0 – ½ (8) = 0

For each chlorine atom, formal charge = 7 – 6 – ½ (2) = 0

For each bromine atom, formal charge = 7 – 6 – ½ (2) = 0

Here, the atoms do not have charges, so no need to mark the charges.

Final structure

The final structure of SiCl₂Br₂ consists of a central silicon atom connected to two chlorine atoms and two bromine atoms through single covalent bonds. In this configuration, the silicon atom satisfies the octet rule by forming four bonding pairs, while each chlorine and bromine atom fulfills its octet by retaining three lone pairs alongside its single shared bond. This arrangement represents the most stable state for the molecule because it results in a formal charge of zero for every atom involved. Consequently, this specific electronic distribution serves as the definitive and most accurate Lewis representation of SiCl₂Br₂.

Next: SOCl₂ Lewis structure

External video

• SiCl2Br2 Lewis Structure: How to Draw the Lewis Structure for SiCl2Br2 – YouTube • Wayne Breslyn

External links

• https://techiescientist.com/sicl2br2-lewis-structure/