XeO3 (xenon trioxide) has one xenon atom and three oxygen atoms. In the lewis structure of XeO3, there are three double bonds around the xenon atom, with three oxygen atoms attached to it. Each oxygen atom has two lone pairs, and the xenon atom has one lone pair.
Steps
Here’s how you can draw the XeO3 lewis structure step by step.
Step #1: draw sketch
Step #2: mark lone pairs
Step #3: mark charges
Step #4: minimize charges
Step #5: minimize charges again (if there are)
Let’s break down each step in detail.
#1 Draw Sketch
- First, determine the total number of valence electrons
In the periodic table, xenon lies in group 18, and oxygen lies in group 16.
Hence, xenon has eight valence electrons and oxygen has six valence electrons.
Since XeO3 has one xenon atom and three oxygen atoms, so…
Valence electrons of one xenon atom = 8 × 1 = 8
Valence electrons of three oxygen atoms = 6 × 3 = 18
And the total valence electrons = 8 + 18 = 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 xenon is less electronegative than oxygen, assume that the central atom is xenon.
Therefore, place xenon in the center and oxygens on either side.
- And finally, draw the rough sketch
#2 Mark Lone Pairs
Here, we have a total of 13 electron pairs. And three Xe — O bonds are already marked. So we have to only mark the remaining ten electron pairs as lone pairs on the sketch.
Also remember that xenon is a period 5 element, so it can keep more than 8 electrons in its last shell. And oxygen 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 oxygens.
So for each oxygen, there are three lone pairs, and for xenon, there is one lone pair.
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 xenon atom, formal charge = 8 – 2 – ½ (6) = +3
For each oxygen atom, formal charge = 6 – 6 – ½ (2) = -1
Here, both xenon and oxygen atoms have charges, so mark them on the sketch as follows:
The above structure is not a stable lewis structure because both xenon and oxygen atoms have charges. Therefore, reduce the charges (as below) by converting lone pairs to bonds.
#4 Minimize Charges
Convert a lone pair of the oxygen atom to make a new Xe — O bond with the xenon atom as follows:
#5 Minimize Charges Again
Since there are charges on xenon and oxygen atoms, again convert a lone pair of the oxygen atom to make a new Xe — O bond with the xenon atom as follows:
#6 Minimize Charges Again
There are still charges on xenon and oxygen atoms, so again convert a lone pair of the oxygen atom to make a new Xe — O bond with the xenon atom as follows:
In the above structure, you can see that the central atom (xenon) forms an octet. Hence, the octet rule is satisfied.
Also, the above structure is more stable than the previous structures. Therefore, this structure is the stable lewis structure of XeO3.
Next: PBr3 Lewis Structure
