SeCl6 Lewis structure

SeCl₆ has one selenium atom and six chlorine atoms.

In SeCl₆ Lewis structure, there are six single bonds around the selenium atom, with six chlorine atoms attached to it, and on each chlorine atom, there are three lone pairs.

Alternative method: Lewis structure of SeCl₆

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 SeCl₆ has one selenium atom and six chlorine atoms, so…

Valence electrons of one selenium atom = 6 × 1 = 6
Valence electrons of six chlorine atoms = 7 × 6 = 42

And the total valence electrons = 6 + 42 = 48

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

• Second, find the total electron pairs

We have a total of 48 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 = 48 ÷ 2 = 24

• 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 24 electron pairs. And six Se — Cl bonds are already marked. So we have to only mark the remaining eighteen 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 zero lone pair because all eighteen 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 selenium atom, formal charge = 6 – 0 – ½ (12) = 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 SeCl₆ contains a central selenium atom connected to six chlorine atoms through single covalent bonds. In this configuration, the selenium atom utilizes an expanded valence shell to accommodate twelve electrons, forming six shared pairs. Within this layout, each of the six chlorine atoms fulfills the octet rule by maintaining three lone pairs alongside its single shared bond. This octahedral arrangement represents the most stable state for the molecule because it results in a formal charge of zero for every atom involved, including the central selenium and all six chlorine atoms. Consequently, this specific electronic distribution serves as the definitive and most accurate Lewis representation of SeCl₆.

Next: SiF₅^– Lewis structure

External links

• https://homework.study.com/explanation/draw-the-lewis-structure-for-secl6-does-the-central-atom-have-an-octet-what-are-the-bond-angles.html
• https://www.numerade.com/ask/question/draw-the-lewis-structure-of-secl6-and-then-determine-the-hybridization-of-the-central-atom-86189/
• https://www.chegg.com/homework-help/questions-and-answers/following-formulas-secl6-1-determine-total-number-valence-electrons-2-draw-good-lewis-stru-q99193236