ClO2- Lewis structure

ClO₂^– (chlorite) has one chlorine atom and two oxygen atoms.

In the ClO₂^– Lewis structure, there is one single bond and one double bond around the chlorine atom, with two oxygen atoms attached to it. The oxygen atom with a single bond has three lone pairs, and the oxygen atom with a double bond has two lone pairs.

Also, there is a negative (-1) charge on the oxygen atom with a single bond.

Alternative method: Lewis structure of ClO₂^–

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

Now the ClO₂^– has a negative (-1) charge, so we have to add one more electron.

So the total valence electrons = 7 + 12 + 1 = 20

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

• Second, find the total electron pairs

We have a total of 20 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 = 20 ÷ 2 = 10

• 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 a total of 10 electron pairs. And two Cl — O bonds are already marked. So we have to only mark the remaining eight electron pairs 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 are two lone pairs.

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 – 4 – ½ (4) = +1

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:

Final structure

The final structure of ClO₂^– contains a central chlorine atom connected to one oxygen atom via a double bond and to the other oxygen atom via a single bond. This specific arrangement allows the chlorine atom to achieve an expanded octet while maintaining two lone pairs, while the single-bonded oxygen carries three lone pairs and the double-bonded oxygen carries two. This configuration is the most stable because it minimizes formal charges, resulting in a -1 charge on the single-bonded oxygen and zero for the remaining atoms, which matches the overall charge of the chlorite ion. Consequently, this resonance-stabilized geometry represents the most accurate Lewis representation of ClO₂^–.

​To complete the representation, draw square brackets around the entire Lewis structure and place a “-” or “-1” sign as a superscript outside the upper right bracket. This notation signifies that the negative charge is a property of the whole chlorite ion.

Next: ClO₃^– Lewis structure

External video

• ClO2- Lewis Structure – How to Draw the Lewis Structure for ClO2- (Chlorite Ion) – YouTube • Wayne Breslyn

External links

• https://techiescientist.com/clo2-lewis-structure/
• https://socratic.org/questions/how-can-i-draw-the-lewis-structure-for-clo2
• https://topblogtenz.com/chlorite-ion-clo2-lewis-structure-molecular-geometry-hybridization-polar-or-nonpolar/
• https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/ClO2-lewis-structure.html
• https://lambdageeks.com/clo2-lewis-structure/