SeS2 Lewis structure

SeS₂ (selenium disulfide) has one selenium atom and two sulfur atoms.

In the SeS₂ Lewis structure, there are two double bonds around the selenium atom, with two sulfur atoms attached to it. Each sulfur atom has two lone pairs, and the selenium atom has one lone pair.

Alternative method: Lewis structure of SeS₂

Rough sketch

• 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 SeS₂ has one selenium atom and two sulfur atoms, so…

Valence electrons of one selenium atom = 6 × 1 = 6
Valence electrons of two sulfur atoms = 6 × 2 = 12

And the total valence electrons = 6 + 12 = 18

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

• Second, find the total electron pairs

We have a total of 18 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 = 18 ÷ 2 = 9

• 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

Lone pair

Here, we have a total of 9 electron pairs. And two Se — S bonds are already marked. So we have to only mark the remaining seven 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 one lone pair.

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 selenium atom, formal charge = 6 – 2 – ½ (4) = +2

For each sulfur atom, formal charge = 6 – 6 – ½ (2) = -1

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

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.

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

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:

Final structure

The final structure of SeS₂ has a central selenium atom linked to two sulfur atoms through double covalent bonds. Within this layout, the selenium atom satisfies the octet rule by forming four total bonds and retaining one lone pair, resulting in a bent molecular geometry. In this arrangement, each sulfur atom fulfills its octet by forming a double bond and maintaining two lone pairs. This configuration represents the most stable state for the molecule because it results in a formal charge of zero for every atom involved. Accordingly, this specific electronic distribution serves as the definitive and most accurate Lewis representation of selenium disulfide.

Next: SeF₂ Lewis structure

External links

• https://oneclass.com/homework-help/chemistry/7056156-lewis-dot-structure-for-ses2.en.html