SeCl4 Lewis structure

SeCl₄ (selenium tetrachloride) has one selenium atom and four chlorine atoms.

In the SeCl₄ Lewis structure, there are four single bonds around the selenium atom, with four chlorine atoms attached to it. Each chlorine atom has three lone pairs, and the selenium atom has one lone pair.

Alternative method: Lewis structure of SeCl₄

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, selenium lies in group 16, and chlorine lies in group 17.

Hence, selenium has six valence electrons and chlorine has seven valence electrons.

Since SeCl₄ has one selenium atom and four chlorine atoms, so…

Valence electrons of one selenium atom = 6 × 1 = 6
Valence electrons of four chlorine atoms = 7 × 4 = 28

And the total valence electrons = 6 + 28 = 34

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

• Second, find the total electron pairs

We have a total of 34 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 = 34 ÷ 2 = 17

• Third, determine the central atom

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

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

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

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 17 electron pairs. And four Se — Cl bonds are already marked. So we have to only mark the remaining thirteen 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 chlorine is a period 3 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.

So for each chlorine, 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 (8) = 0

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

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

Final structure

The final structure of SeCl₄ features a central selenium atom linked to four chlorine atoms through single covalent bonds. Within this configuration, the selenium atom utilizes an expanded octet to accommodate ten valence electrons, which includes four bonding pairs and one lone pair. Each chlorine atom satisfies the octet rule by maintaining three lone pairs of its own. This specific arrangement is the most stable because it results in formal charges of zero for all atoms, representing the most energetically favorable distribution for the molecule. Consequently, this electronic pattern serves as the definitive and most accurate Lewis representation of selenium tetrachloride.

Next: TeCl₄ Lewis structure

External video

• SeCl4 Lewis Structure: How to Draw the Lewis Structure for SeCl4 – YouTube • Wayne Breslyn

External links

• https://techiescientist.com/secl4-lewis-structure/
• https://lambdageeks.com/secl4-lewis-structure/