SF4 Lewis structure

SF₄ (sulfur tetrafluoride) has one sulfur atom and four fluorine atoms.

In the SF₄ Lewis structure, there are four single bonds around the sulfur atom, with four fluorine atoms attached to it. Each fluorine atom has three lone pairs, and the sulfur atom has one lone pair.

Alternative method: Lewis structure of SF₄

Rough sketch

• First, determine the total number of valence electrons

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 SF₄ has one sulfur atom and four fluorine atoms, so…

Valence electrons of one sulfur atom = 6 × 1 = 6
Valence electrons of four fluorine atoms = 7 × 4 = 28

And the total valence electrons = 6 + 28 = 34

Learn how to find: Sulfur valence electrons and Fluorine 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 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

Lone pair

Here, we have a total of 17 electron pairs. And four S — F bonds are already marked. So we have to only mark the remaining thirteen 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 carbon 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 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 sulfur atom, formal charge = 6 – 2 – ½ (8) = 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.

Final structure

The final structure of SF₄ features a central sulfur atom connected to four fluorine atoms through single covalent bonds. In this layout, the sulfur atom serves as an exception to the octet rule, utilizing an expanded valence shell to accommodate ten electrons through four bonding pairs and one lone pair. Each fluorine atom satisfies its octet by retaining three lone pairs alongside its single shared bond with the sulfur. This arrangement is the most stable because it results in formal charges of zero for every atom in the molecule, representing the most energetically favorable state. Accordingly, this specific electronic distribution serves as the definitive and most accurate Lewis representation of sulfur tetrafluoride.

Next: H₂S Lewis structure

External video

• SF4 Lewis Structure: How to Draw the Lewis Structure for SF4 – YouTube • Wayne Breslyn

External links

• https://www.chemistryscl.com/general/SF4-lewis-structure/index.php
• https://techiescientist.com/sf4-lewis-structure/
• https://geometryofmolecules.com/sf4-lewis-structure-polarity/
• https://whatsinsight.org/sf4-lewis-structure/
• https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/SF4-lewis-structure.html
• https://lambdageeks.com/sf4-lewis-structure/
• https://topblogtenz.com/sf4-lewis-structure-molecular-geometry-bond-angle-hybridization/