Lewis structure of O3

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Lewis structure of O3
Lewis structure of O3 | Image: Root Memory

The Lewis structure of O3 contains one double bond and one single bond, with one oxygen in the center, and two other oxygens on either side. The left oxygen atom has two lone pairs, the right oxygen atom has three lone pairs, and the center oxygen atom has one lone pair.

Plus, there is a positive (+1) charge on the center oxygen atom, and a negative (-1) charge on the right oxygen atom.

Steps

By using the following steps, you can easily draw the Lewis structure of O3:

#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Complete octet on central atom
#5 Calculate formal charge and check stability

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… oxygen is a group 16 element. Hence, oxygen has six valence electrons.

Now O3 has three oxygen atoms.

So the total number of valence electrons = valence electrons of oxygen atom × 3

Therefore, the total number of valence electrons = 6 × 3 = 18

  • Now decide the central atom

There are three oxygen atoms in O3. Hence, we can assume any one as the central atom. Let’s assume that center oxygen is the central atom.

So now, put three oxygens next to each other. And draw the rough skeleton structure for the Lewis structure of O3 something like this:

Skeleton structure for Lewis structure of O3 | Image: Root Memory

#2 Show chemical bond

Place two electrons between the atoms to show a chemical bond. Since center oxygen is surrounded by two other oxygens, use four electrons to show two chemical bonds as follows:

Two chemical bonds shown between atoms | Image: Root Memory

#3 Mark lone pairs

As calculated earlier, we have a total of 18 valence electrons. And in the above structure, we have already used four valence electrons. Hence, fourteen valence electrons are remaining.

Two valence electrons represent one lone pair. So fourteen valence electrons = seven lone pairs.

Note that oxygen 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 left oxygen and right oxygen, so left oxygen and right oxygen will get three lone pairs. And the central atom (center oxygen) will get one lone pair.

So the Lewis structure of O3 looks something like this:

Lone pairs marked on Lewis structure of O3 | Image: Root Memory

In the above structure, you can see that the octet is completed on outside atoms. But, the central atom (center oxygen) doesn’t form an octet.

So in the next step, we have to complete the octet on the central atom.

#4 Complete octet on central atom

Remember that oxygen is a period 2 element, so it can not keep more than 8 electrons in its last shell.

Now the center oxygen already has six valence electrons. Hence, the center oxygen needs two more valence electrons to complete its octet.

So convert one lone pair from the left oxygen atom to make a new bond with the center oxygen atom. And then, the Lewis structure of O3 looks something like this:

Lone pair of left oxygen is converted, and octet is completed on atoms | Image: Root Memory

In the above structure, you can see that the octet is completed on the central atom (center oxygen), 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.

#5 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 left oxygen atom

Valence electrons = 6
Nonbonding electrons = 4
Bonding electrons = 4

Formal charge = 6 – 4 – ½ (4) = 0

  • For center oxygen atom

Valence electrons = 6
Nonbonding electrons = 2
Bonding electrons = 6

Formal charge = 6 – 2 – ½ (6) = +1

  • For right oxygen atom

Valence electrons = 6
Nonbonding electrons = 6
Bonding electrons = 2

Formal charge = 6 – 6 – ½ (2) = -1

Mention the formal charges of atoms on the structure. So the Lewis structure of O3 looks something like this:

Formal charges are calculated, and got the most stable Lewis structure of O3 | Image: Root Memory

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 O3.

And each horizontal line drawn in the above structure represents a pair of bonding valence electrons.

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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.

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