ClO4- Lewis structure

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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.

Steps

Use these steps to correctly draw the ClO₄^– Lewis structure:

#1 First draw a rough sketch
#2 Mark lone pairs on the atoms
#3 Calculate and mark formal charges on the atoms, if required
#4 Convert lone pairs of the atoms, and minimize formal charges
#5 Repeat step 4 if needed, until all charges are minimized, to get a stable Lewis structure

Let’s discuss each step in more detail.

#1 First draw a 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

#2 Mark lone pairs on the atoms

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:

#3 Calculate and mark formal charges on the atoms, if required

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.

#4 Convert lone pairs of the atoms, and minimize formal charges

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

#5 Repeating step 4 to get a stable Lewis structure

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:

#6 Minimize charges again

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:

In the above structure, you can see that the central atom (chlorine) forms an octet. And the outside atoms (oxygens) also form an octet. Hence, the octet rule is satisfied.

Now there is still a negative (-1) charge on the oxygen atom.

This is okay, because the structure with a negative charge on the most electronegative atom is the best Lewis structure. And in this case, the most electronegative element is oxygen.

Also, the above structure is more stable than the previous structures. Therefore, this structure is the most stable Lewis structure of ClO₄^–.

And since the ClO₄^– has a negative (-1) charge, mention that charge on the Lewis structure by drawing brackets as follows:

Next: ClO^– Lewis structure

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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