Lewis structure of ClO2

ClO₂ (chlorine dioxide) has one chlorine atom and two oxygen atoms.

In the Lewis structure of ClO₂, there are two double bonds around the chlorine atom, with two oxygen atoms attached to it. Each oxygen atom has two lone pairs, and the chlorine atom has one lone pair and one unpaired electron.

Alternative method: ClO₂ Lewis structure

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, chlorine lies in group 17, and oxygen lies in group 16.

Hence, chlorine has seven valence electrons and oxygen has six valence electrons.

Since ClO₂ has one chlorine atom and two oxygen atoms, so…

Valence electrons of one chlorine atom = 7 × 1 = 7
Valence electrons of two oxygen atoms = 6 × 2 = 12

And the total valence electrons = 7 + 12 = 19

Learn how to find: Chlorine valence electrons and Oxygen valence electrons

• Second, find the total electron pairs

We have a total of 19 valence electrons. And when we divide this value by two, we get the value of total electron pairs.

But 19 can not be divided by two. Hence, there are a total of 9 electron pairs and one unpaired electron.

• Third, determine the central atom

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

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

Therefore, place chlorine in the center and oxygens on either side.

• And finally, draw the rough sketch

Lone pair

Here, we have 9 electron pairs and one unpaired electron. And two Cl — O bonds are already marked. So we have to only mark the remaining seven electron pairs and one unpaired electron as lone pairs on the sketch.

Also remember that chlorine is a 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.

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 chlorine, there is one lone pair and one unpaired electron.

Mark the lone pairs on the sketch as follows:

Formal charge

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

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

For chlorine atom, formal charge = 7 – 3 – ½ (4) = +2

For each oxygen atom, formal charge = 6 – 6 – ½ (2) = -1

Here, both chlorine and oxygen atoms have charges, so mark them on the sketch as follows:

The above structure is not a stable Lewis structure because both chlorine and oxygen atoms have charges. Therefore, reduce the charges (as below) by converting lone pairs to bonds.

Convert a lone pair of the oxygen atom to make a new Cl — O bond with the chlorine atom as follows:

Since there are charges on chlorine and oxygen atoms, again convert a lone pair of the oxygen atom to make a new Cl — O bond with the chlorine atom as follows:

Final structure

The final structure of ClO₂ has a central chlorine atom linked to two oxygen atoms. In this configuration, the chlorine atom utilizes an expanded valence shell to accommodate eleven electrons, which consist of two double bonds to the oxygen atoms and three additional electrons (one lone pair and one unpaired electron). Within this arrangement, each oxygen atom fulfills its octet by forming a double bond with the chlorine and retaining two lone pairs. This layout represents the most stable state for the molecule because it results in a formal charge of zero for every atom involved, despite chlorine functioning as an odd-electron molecule. Therefore, this specific electronic distribution serves as the definitive and most accurate Lewis representation of chlorine dioxide.

Next: C₄H₁₀ Lewis structure

External video

• How to Draw the Lewis Structure for ClO2 (Chlorine dioxide) – YouTube • Wayne Breslyn

External links

• https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/ClO2lewis-structure.html