SF6 (sulfur hexafluoride) has one sulfur atom and six fluorine atoms. In the lewis structure of SF6, 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.
Here’s how you can draw the SF6 lewis structure step by step.
Step #1: draw sketch
Step #2: mark lone pairs
Step #3: mark charges (if there are)
Let’s break down each step in detail.
#1 Draw Sketch
- First, determine the total number of valence electrons
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
#2 Mark Lone Pairs
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:
#3 Mark Charges
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.
And in the above structure, you can see that the central atom (sulfur) forms an octet. Hence, the octet rule is satisfied.
Therefore, this structure is the stable lewis structure of SF6.
Next: PH3 Lewis Structure