SbF3 Lewis structure

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SbF3 Lewis Structure
SbF3 Lewis structure

SbF3 (antimony trifluoride) has one antimony atom and three fluorine atoms.

In SbF3 Lewis structure, there are three single bonds around the antimony atom, with three fluorine atoms attached to it. Each fluorine atom has three lone pairs, and the antimony atom has one lone pair.


To properly draw the SbF3 Lewis structure, follow these steps:

#1 Draw a rough sketch of the structure
#2 Next, indicate lone pairs on the atoms
#3 Indicate formal charges on the atoms, if necessary

Let’s break down each step in more detail.

#1 Draw a rough sketch of the structure

  • First, determine the total number of valence electrons
Periodic table

In the periodic table, antimony lies in group 15, and fluorine lies in group 17.

Hence, antimony has five valence electrons and fluorine has seven valence electrons.

Since SbF3 has one antimony atom and three fluorine atoms, so…

Valence electrons of one antimony atom = 5 × 1 = 5
Valence electrons of three fluorine atoms = 7 × 3 = 21

And the total valence electrons = 5 + 21 = 26

  • Second, find the total electron pairs

We have a total of 26 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 = 26 ÷ 2 = 13

  • Third, determine the central atom

We have to place the least electronegative atom at the center.

Since antimony is less electronegative than fluorine, assume that the central atom is antimony.

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

  • And finally, draw the rough sketch
SbF3 Lewis Structure (Step 1)
Rough sketch of SbF3 Lewis structure

#2 Next, indicate lone pairs on the atoms

Here, we have a total of 13 electron pairs. And three Sb — F bonds are already marked. So we have to only mark the remaining ten electron pairs as lone pairs on the sketch.

Also remember that antimony is a period 5 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 antimony, there is one lone pair.

Mark the lone pairs on the sketch as follows:

SbF3 Lewis Structure (Step 2)
Lone pairs marked, and got the stable Lewis structure of SbF3

#3 Indicate formal charges on the atoms, if necessary

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

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

For antimony atom, formal charge = 5 – 2 – ½ (6) = 0

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

Here, both antimony 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 (antimony) 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 SbF3.

Next: AsO33- Lewis structure

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