Lewis structure of SeS2

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The Lewis structure of SeS₂ contains two double bonds, with selenium in the center, and two sulfurs on either side. There are two lone pairs on each sulfur atom, and one lone pair on the selenium atom.

Steps

By using the following steps, you can easily draw the Lewis structure of SeS₂.

#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Complete octet on central atom
#5 Calculate formal charge and check stability
#6 Convert lone pair and calculate formal charge again (if formal charges are not closer to zero)

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… both selenium and sulfur are the group 16 elements. Hence, both selenium and sulfur have six valence electrons.

Now SeS₂ has one selenium atom and two sulfur atoms.

So the total number of valence electrons = valence electrons of selenium atom + (valence electrons of sulfur atom × 2)

Therefore, the total number of valence electrons = 6 + 12 = 18

• 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 selenium and sulfur as follows:

Electronegativity value of selenium = 2.55
Electronegativity value of sulfur = 2.58

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

So now, put selenium in the center and sulfurs on either side. And draw the rough skeleton structure for the Lewis structure of SeS₂ something like this:

Also read: How to draw Lewis structure of TeCl₄ (4 steps)

#2 Show chemical bond

Place two electrons between the atoms to show a chemical bond. Since selenium is surrounded by two sulfurs, use four electrons to show two chemical bonds as follows:

#3 Mark lone pairs

As calculated earlier, we have a total of 18 valence electrons. And in the above structure, we have already used four valence electrons. Hence, fourteen valence electrons are remaining.

Two valence electrons represent one lone pair. So fourteen valence electrons = seven lone pairs.

Note that selenium is 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 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 sulfurs, so each sulfur will get three lone pairs. And the central atom (selenium) will get one lone pair.

So the Lewis structure of SeS₂ looks something like this:

In the above structure, you can see that the octet is completed on outside atoms. But, the central atom (selenium) doesn’t form an octet.

So in the next step, we have to complete the octet on the central atom.

Also read: How to draw Lewis structure of C₂Br₂ (5 steps)

#4 Complete octet on central atom

Remember that selenium is a period 4 element, so it can keep more than 8 electrons in its last shell.

Now selenium already has six valence electrons. Hence, selenium needs two more valence electrons to complete its octet.

So convert one lone pair from one sulfur atom to make a new bond with the selenium atom. And then, the Lewis structure of SeS₂ looks something like this:

In the above structure, you can see that the octet is completed on the central atom (selenium), 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.

#5 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 selenium atom

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

Formal charge = 6 – 2 – ½ (6) = +1

• For left sulfur atom

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

Formal charge = 6 – 6 – ½ (2) = -1

• For right sulfur atom

Valence electrons = 6
Nonbonding electrons = 4
Bonding electrons = 4

Formal charge = 6 – 4 – ½ (4) = 0

Mention the formal charges of atoms on the structure. So the Lewis structure of SeS₂ looks something like this:

In the above structure, you can see that the formal charges of atoms are not closer to zero. Therefore, convert lone pair and calculate formal charge again.

Also read: How to draw Lewis structure of BrO₄^– (5 steps)

#6 Convert lone pair and calculate formal charge again

As mentioned earlier, selenium is a period 4 element, so it can keep more than 8 electrons in its last shell.

So again convert one lone pair from the left sulfur atom to make a new bond with the selenium atom. And then, the Lewis structure of SeS₂ looks something like this:

Now one last thing we need to do is, calculate the formal charge again and check the stability of the above structure.

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 selenium atom

Valence electrons = 6
Nonbonding electrons = 2
Bonding electrons = 8

Formal charge = 6 – 2 – ½ (8) = 0

• For each sulfur atom

Valence electrons = 6
Nonbonding electrons = 4
Bonding electrons = 4

Formal charge = 6 – 4 – ½ (4) = 0

Mention the formal charges of atoms on the structure. So the Lewis structure of SeS₂ looks something like this:

In the above structure, you can see that the formal charges of both (selenium and sulfur) are zero. Therefore, this is the stable Lewis structure of SeS₂.

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

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Related

• Lewis structure of TeCl₄
• Lewis structure of C₂Br₂
• Lewis structure of BrO₄^–
• Lewis structure of HOCN
• Lewis structure of SF₅^–

External links

• SeS2 Lewis Structure in 6 Steps (With Images) – Pediabay
• Draw the Lewis structure for Ses2 – Chegg
• What is the Lewis dot structure for SSE2? – Quora
• Selenium disulfide | SeS2 | CID 24087 – National Institutes of Health (.gov)
• What is the Lewis structure of SeS2? – Quizlet
• How many valence electrons should be drawn in the Lewis structure of SeS2? – Homework.Study.com
• Consider the SeS2 molecule. Using Lewis structure and formal charge arguments, describe it in detail – Brainly
• Draw the Lewis structure for SeS2 – Numerade
• draw the lewis dot structure for SeS2 – Bartleby
• Draw the Lewis structure of SeS2 – OneClass
• What is the molecular shape of SeS2? – Answers