SiCl4 Lewis structure

SiCl₄ (silicon tetrachloride) has one silicon atom and four chlorine atoms.

In the SiCl₄ Lewis structure, there are four single bonds around the silicon atom, with four chlorine atoms attached to it, and on each chlorine atom, there are three lone pairs.

Alternative method: Lewis structure of SiCl₄

Rough sketch

• First, determine the total number of valence electrons

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

Hence, silicon has four valence electrons and chlorine has seven valence electrons.

Since SiCl₄ has one silicon atom and four chlorine atoms, so…

Valence electrons of one silicon atom = 4 × 1 = 4
Valence electrons of four chlorine atoms = 7 × 4 = 28

And the total valence electrons = 4 + 28 = 32

Learn how to find: Silicon valence electrons and Chlorine 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, assume that the central atom is silicon.

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

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 16 electron pairs. And four Si — Cl 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.

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

So for each chlorine, 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

Here, both silicon and chlorine atoms do not have charges, so no need to mark the charges.

Final structure

The final structure of SiCl₄ features a central silicon atom connected to four chlorine atoms through single covalent bonds. In this arrangement, the silicon atom satisfies the octet rule by forming four bonding pairs, while each chlorine atom fulfills its octet by maintaining three lone pairs of its own. This specific setup is the most stable because it results in formal charges of zero for all atoms involved, representing the most energetically favorable state for the molecule. Consequently, this electronic distribution serves as the definitive and most accurate Lewis representation of silicon tetrachloride.

Next: BrO₃^– Lewis structure

External video

• SiCl4 Lewis Structure – How to Draw the Lewis Structure for SiCl4 – YouTube • Wayne Breslyn

External links

• https://topblogtenz.com/sicl4-lewis-structure-molecular-geometry-polarity/
• https://www.chemistryscl.com/general/silicon-tetrachloride-SiCl4-lewis-structure/index.php
• https://lambdageeks.com/sicl4-lewis-structure/
• https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/SiCl4-lewis-structure.html
• https://sciedutut.com/how-to-draw-a-sicl4-lewis-structure/