The Lewis structure of XeF3– contains three single bonds, with xenon in the center, and three fluorines on either side. There are three lone pairs on each atom.
Plus, there is a negative (-1) charge on the xenon atom.
Steps
By using the following steps, you can easily draw the Lewis structure of XeF3–.
#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Calculate formal charge and check stability (if octet is already completed on central atom)
Let’s one by one discuss each step in detail.
#1 Draw skeleton
In this step, first calculate the total number of valence electrons. And then, decide the central atom.
- Let’s calculate the total number of valence electrons
We know that… xenon is a group 18 element and fluorine is a group 17 element. Hence, xenon has eight valence electrons and fluorine has seven valence electrons.
Now XeF3– has one xenon atom and three fluorine atoms.
So the total number of valence electrons = valence electrons of xenon atom + (valence electrons of fluorine atom × 3)
And XeF3– has a negative (-1) charge, so we have to add one more electron.
Therefore, the total number of valence electrons = 8 + 21 + 1 = 30
- Now decide the central atom
The atom with the least electronegative value is placed at the center. By looking at the periodic table, we get the electronegativity values for xenon and fluorine as follows:
Electronegativity value of xenon = 2.6
Electronegativity value of fluorine = 3.98
Obviously, xenon is less electronegative than fluorine. Hence, assume that xenon is the central atom.
So now, put xenon in the center and fluorines on either side. And draw the rough skeleton structure for the Lewis structure of XeF3– something like this:
Also read: How to draw XeF3+ Lewis structure (4 steps)
#2 Show chemical bond
Place two electrons between the atoms to show a chemical bond. Since xenon is surrounded by three fluorines, use six electrons to show three chemical bonds as follows:
Also read: How to draw Lewis structure of CHF3 (4 steps)
#3 Mark lone pairs
As calculated earlier, we have a total of 30 valence electrons. And in the above structure, we have already used six valence electrons. Hence, twenty-four valence electrons are remaining.
Two valence electrons represent one lone pair. So twenty-four valence electrons = twelve lone pairs.
Note that xenon 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.
Also, make sure that you start marking these lone pairs on outside atoms first. And then, on the central atom.
The outside atoms are fluorines, so each fluorine will get three lone pairs. And the central atom (xenon) will also get three lone pairs.
So the Lewis structure of XeF3– looks something like this:
In the above structure, you can see that the octet is completed on the central atom (xenon), and also on the outside atoms. Therefore, the octet rule is satisfied.
After completing the octet, one last thing we need to do is, calculate the formal charge and check the stability of the above structure.
Also read: How to draw Lewis structure of XeF5+ (4 steps)
#4 Calculate formal charge and check stability
The following formula is used to calculate the formal charges on atoms:
Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons
Collect the data from the above structure and then, write it down below as follows:
- For xenon atom
Valence electrons = 8
Nonbonding electrons = 6
Bonding electrons = 6
Formal charge = 8 – 6 – ½ (6) = -1
- For each fluorine atom
Valence electrons = 7
Nonbonding electrons = 6
Bonding electrons = 2
Formal charge = 7 – 6 – ½ (2) = 0
Mention the formal charges of atoms on the structure. So the Lewis structure of XeF3– looks something like this:
In the above structure, you can see that the formal charges of atoms are closer to zero. Therefore, this is the most stable Lewis structure of XeF3–.
And each horizontal line drawn in the above structure represents a pair of bonding valence electrons.
Now XeF3– is an ion having a negative (-1) charge, so draw brackets around the above Lewis structure and mention that charge on the top right corner. And then, the Lewis structure of XeF3– looks something like this:
Related
- XeF3+ Lewis structure
- Lewis structure of CHF3
- Lewis structure of XeF5+
- Lewis structure of ClBr3
- Lewis structure of CH3COO–
External links
- Draw the Lewis Structure of XeF3+ – Chegg
- Draw the Lewis Structure of XeF3+ – Brainly
- What is the Lewis structure of XeF3+? – OneClass
Deep
Rootmemory.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.