ClO2 Lewis structure

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The ClO₂ Lewis structure contains two double bonds, with chlorine in the center, and two oxygens on either side. There are two lone pairs on each oxygen atom, and the chlorine atom has one lone pair and one unpaired electron.

Steps

By using the following steps, you can easily draw the ClO₂ Lewis structure.

#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Complete octet on central atom
#5 Calculate formal charge and check stability
#6 Convert lone pair and calculate formal charge again (if formal charges are not closer to zero)

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… chlorine is a group 17 element and oxygen is a group 16 element. Hence, chlorine has seven valence electrons and oxygen has six valence electrons.

Now ClO₂ has one chlorine atom and two oxygen atoms.

So the total number of valence electrons = valence electrons of chlorine atom + (valence electrons of oxygen atom × 2)

Therefore, the total number of valence electrons = 7 + 12 = 19

• 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 chlorine and oxygen as follows:

Electronegativity value of chlorine = 3.16
Electronegativity value of oxygen = 3.44

Obviously, chlorine is less electronegative than oxygen. Hence, assume that chlorine is the central atom.

So now, put chlorine in the center and oxygens on either side. And draw the rough skeleton structure for the ClO₂ Lewis structure something like this:

Also read: How to draw Lewis structure of SCl₄ (4 steps)

#2 Show chemical bond

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

#3 Mark lone pairs

As calculated earlier, we have a total of 19 valence electrons. And in the above structure, we have already used four valence electrons. Hence, fifteen valence electrons are remaining.

Two valence electrons represent one lone pair. So fourteen valence electrons = seven lone pairs. Also, we have one unpaired electron.

Note that chlorine is period 3 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.

Also, make sure that you start marking these lone pairs on outside atoms first. And then, on the central atom.

The outside atoms are oxygens, so each oxygen will get three lone pairs. And the central atom (chlorine) will get one lone pair and one unpaired electron.

So the ClO₂ Lewis structure looks something like this:

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

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

Also read: How to draw Lewis structure of SeO₃ (6 steps)

#4 Complete octet on central atom

Remember that chlorine is a period 3 element, so it can keep more than 8 electrons in its last shell.

Now chlorine already has seven valence electrons. Hence, chlorine needs one more valence electron to complete its octet.

So convert one lone pair from one oxygen atom to make a new bond with the chlorine atom. And then, the ClO₂ Lewis structure looks something like this:

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

Valence electrons = 7
Nonbonding electrons = 3
Bonding electrons = 6

Formal charge = 7 – 3 – ½ (6) = +1

• For left oxygen atom

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

Formal charge = 6 – 6 – ½ (2) = -1

• For right oxygen atom

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

Formal charge = 6 – 4 – ½ (4) = 0

Mention the formal charges of atoms on the structure. So the ClO₂ Lewis structure looks something like this:

In the above structure, you can see that the formal charges of atoms are not closer to zero. Therefore, convert lone pair and calculate formal charge again.

Also read: How to draw Lewis structure of H₂SO₃ (5 steps)

#6 Convert lone pair and calculate formal charge again

As mentioned earlier, chlorine is a period 3 element, so it can keep more than 8 electrons in its last shell.

So again convert one lone pair from the left oxygen atom to make a new bond with the chlorine atom. And then, the ClO₂ Lewis structure looks something like this:

Now one last thing we need to do is, calculate the formal charge again and check the stability of the above structure.

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 chlorine atom

Valence electrons = 7
Nonbonding electrons = 3
Bonding electrons = 8

Formal charge = 7 – 3 – ½ (8) = 0

• For each oxygen atom

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

Formal charge = 6 – 4 – ½ (4) = 0

Mention the formal charges of atoms on the structure. So the ClO₂ Lewis structure looks something like this:

In the above structure, you can see that the formal charges of both (chlorine and oxygen) are zero. Therefore, this is the stable Lewis structure of ClO₂.

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

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Related

• Lewis structure of SCl₄
• Lewis structure of SeO₃
• Lewis structure of H₂SO₃
• Lewis structure of CCl₂F₂
• Lewis structure of HSO₄^–

External links

• Lewis Structure for ClO2 – The University of Maryland
• Drawing the Lewis Structure for ClO2 – The Geoexchange
• Lewis Dot of Chlorine Dioxide ClO2 – Kent’s Chemistry
• ClO2 Lewis Structure in 5 Steps (With Images) – Pediabay
• Draw and explain the Lewis structure for the ClO₂ molecule, which is an exception to the octet rule – Homework.Study.com
• Lewis structure for ClO2? – Answers