SeS3 Lewis structure

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SeS₃ has one selenium atom and three sulfur atoms.

In SeS₃ Lewis structure, there are three double bonds around the selenium atom, with three sulfur atoms attached to it, and on each sulfur atom, there are two lone pairs.

Contents

Steps

To properly draw the SeS₃ Lewis structure, follow these steps:

#1 Draw a rough sketch of the structure
#2 Next, indicate lone pairs on the atoms
#3 Indicate formal charges on the atoms, if necessary
#4 Minimize formal charges by converting lone pairs of the atoms
#5 Repeat step 4 if necessary, until all charges are minimized

Let’s break down each step in more detail.

#1 Draw a rough sketch of the structure

First, determine the total number of valence electrons

In the periodic table, both selenium and sulfur lie in group 16.

Hence, both selenium and sulfur have six valence electrons.

Since SeS₃ has one selenium atom and three sulfur atoms, so…

Valence electrons of one selenium atom = 6 × 1 = 6
Valence electrons of three sulfur atoms = 6 × 3 = 18

And the total valence electrons = 6 + 18 = 24

Learn how to find: Selenium valence electrons and Sulfur valence electrons

Second, find the total electron pairs

We have a total of 24 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 = 24 ÷ 2 = 12

Third, determine the central atom

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

Since selenium is less electronegative than sulfur, assume that the central atom is selenium.

Therefore, place selenium in the center and sulfurs on either side.

And finally, draw the rough sketch

SeS3 Lewis Structure (Step 1) — Rough sketch of SeS₃ Lewis structure | Image: Learnool

#2 Next, indicate lone pairs on the atoms

Here, we have a total of 12 electron pairs. And three Se — S bonds are already marked. So we have to only mark the remaining nine electron pairs as lone pairs on the sketch.

Also remember that selenium is a period 4 element, so it can keep more than 8 electrons in its last shell. And sulfur is a period 3 element, so it can also keep more than 8 electrons in its last shell.

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

So for each sulfur, there are three lone pairs, and for selenium, there is zero lone pair because all nine electron pairs are over.

Mark the lone pairs on the sketch as follows:

SeS3 Lewis Structure (Step 2) — Lone pairs marked on SeS₃ Lewis structure | Image: Learnool

#3 Indicate formal charges on the atoms, if necessary

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

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

For selenium atom, formal charge = 6 – 0 – ½ (6) = +3

For each sulfur atom, formal charge = 6 – 0 – ½ (6) = -1

Here, both selenium and sulfur atoms have charges, so mark them on the sketch as follows:

SeS3 Lewis Structure (Step 3) — Formal charges marked on SeS₃ Lewis structure | Image: Learnool

The above structure is not a stable Lewis structure because both selenium and sulfur atoms have charges. Therefore, reduce the charges (as below) by converting lone pairs to bonds.

#4 Minimize formal charges by converting lone pairs of the atoms

Convert a lone pair of the sulfur atom to make a new Se — S bond with the selenium atom as follows:

SeS3 Lewis Structure (Step 4) — Lone pair of left sulfur is converted, but still there are charges | Image: Learnool

#5 Repeat step 4 (minimize charges again)

Since there are charges on selenium and sulfur atoms, again convert a lone pair of the sulfur atom to make a new Se — S bond with the selenium atom as follows:

SeS3 Lewis Structure (Step 5) — Lone pair of right sulfur is converted, but still there are charges | Image: Learnool

#6 Minimize charges again

There are still charges on selenium and sulfur atoms, so again convert a lone pair of the sulfur atom to make a new Se — S bond with the selenium atom as follows:

SeS3 Lewis Structure (Step 6) — Lone pair of top sulfur is converted, and got the stable Lewis structure of SeS₃ | Image: Learnool

In the above structure, you can see that the central atom (selenium) forms an octet. And the outside atoms (sulfurs) also form an octet. Hence, the octet rule is satisfied.

Also, the above structure is more stable than the previous structures. Therefore, this structure is the stable Lewis structure of SeS₃.

Next: IBr₅ Lewis structure

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Deep

Learnool.com was founded by Deep Rana, who is a mechanical engineer by profession and a blogger by passion. He has a good conceptual knowledge on different educational topics and he provides the same on this website. He loves to learn something new everyday and believes that the best utilization of free time is developing a new skill.