SF6 Lewis structure

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SF6 Lewis Structure
SF6 Lewis structure | Image: Learnool

SF6 (sulfur hexafluoride) has one sulfur atom and six fluorine atoms.

In the SF6 Lewis structure, there are six single bonds around the sulfur atom, with six fluorine atoms attached to it, and on each fluorine atom, there are three lone pairs.

Steps

Here’s how you can easily draw the SF6 Lewis structure step by step:

#1 Draw a rough skeleton structure
#2 Mention lone pairs on the atoms
#3 If needed, mention formal charges on the atoms

Now, let’s take a closer look at each step mentioned above.

#1 Draw a rough skeleton structure

  • First, determine the total number of valence electrons
Periodic table | Image: Learnool

In the periodic table, sulfur lies in group 16, and fluorine lies in group 17.

Hence, sulfur has six valence electrons and fluorine has seven valence electrons.

Since SF6 has one sulfur atom and six fluorine atoms, so…

Valence electrons of one sulfur atom = 6 × 1 = 6
Valence electrons of six fluorine atoms = 7 × 6 = 42

And the total valence electrons = 6 + 42 = 48

  • 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 sulfur is less electronegative than fluorine, assume that the central atom is sulfur.

Therefore, place sulfur in the center and fluorines on either side.

  • And finally, draw the rough sketch
SF6 Lewis Structure (Step 1)
Rough sketch of SF6 Lewis structure | Image: Learnool

#2 Mention lone pairs on the atoms

Here, we have a total of 24 electron pairs. And six S — F bonds are already marked. So we have to only mark the remaining eighteen electron pairs as lone pairs on the sketch.

Also remember that sulfur is a period 3 element, so it can keep more than 8 electrons in its last shell. And fluorine is a period 2 element, so it can not keep more than 8 electrons in its last shell.

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

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

Mark the lone pairs on the sketch as follows:

SF6 Lewis Structure (Step 2)
Lone pairs marked, and got the stable Lewis structure of SF6 | Image: Learnool

#3 If needed, mention formal charges on the atoms

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

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

For sulfur atom, formal charge = 6 – 0 – ½ (12) = 0

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

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

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

Therefore, this structure is the stable Lewis structure of SF6.

Next: PH3 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.

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