# 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.

Contents

## Steps

Here’s how you can easily draw the SF4 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

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

• 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

### #2 Mention lone pairs on the atoms

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:

### #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 – 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.

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 SF4.

Next: H2S Lewis structure