ClO4- Lewis structure

ClO₄^– (perchlorate) has one chlorine atom and four oxygen atoms.

In the ClO₄^– Lewis structure, there is one single bond and three double bonds around the chlorine atom, with four oxygen atoms attached to it. The oxygen atom with a single bond has three lone pairs, and the three oxygen atoms with double bonds have two lone pairs.

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

Alternative method: Lewis structure of ClO₄^–

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 ClO₄^– has one chlorine atom and four oxygen atoms, so…

Valence electrons of one chlorine atom = 7 × 1 = 7
Valence electrons of four oxygen atoms = 6 × 4 = 24

Now the ClO₄^– has a negative (-1) charge, so we have to add one more electron.

So the total valence electrons = 7 + 24 + 1 = 32

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

• Second, find the total electron pairs

We have a total of 32 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 = 32 ÷ 2 = 16

• 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 16 electron pairs. And four Cl — O bonds are already marked. So we have to only mark the remaining twelve 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 is zero lone pair because all twelve electron pairs are over.

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 – 0 – ½ (8) = +3

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:

There are still charges on chlorine and oxygen atoms, so 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 ClO₄^– involves a central chlorine atom connected to four oxygen atoms. In this arrangement, the chlorine atom utilizes an expanded octet to form three double bonds and one single bond with the oxygens. This specific configuration allows each oxygen atom involved in a double bond to retain two lone pairs, while the single-bonded oxygen atom maintains three lone pairs. This setup is the most stable because it minimizes formal charges across the ion, resulting in a formal charge of zero on the chlorine and the three double-bonded oxygens, and a -1 charge on the single-bonded oxygen. Consequently, this electronic distribution serves as the definitive and most accurate Lewis representation of the perchlorate ion.

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 ion.

Next: ClO^– Lewis structure

External video

• ClO4- Lewis Structure – How to Draw the Lewis Structure for ClO4- (Perchlorate Ion) – YouTube • Wayne Breslyn

External links

• https://www.chemistryscl.com/general/lewis-structure-of-ClO4-/
• https://techiescientist.com/clo4-lewis-structure/
• https://lambdageeks.com/clo4-lewis-structure/
• https://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/ClO4-lewis-structure.html