Lewis structure of ClO3-

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The Lewis structure of ClO₃^– contains two double bonds and one single bond, with chlorine in the center, and three oxygens on either side. The left oxygen atom and right oxygen atom have two lone pairs, the top oxygen atom has three lone pairs, and the chlorine atom has one lone pair.

Plus, there is a negative (-1) charge on the top oxygen atom.

Steps

By using the following steps, you can easily draw the Lewis structure of ClO₃^–:

#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Calculate formal charge and check stability (if octet is already completed on central atom)
#5 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 ClO₃^– has one chlorine atom and three oxygen atoms.

So the total number of valence electrons = valence electrons of chlorine atom + (valence electrons of oxygen atom × 3)

And ClO₃^– has a negative (-1) charge, so we have to add one more electron.

Therefore, the total number of valence electrons = 7 + 18 + 1 = 26

• 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 Lewis structure of ClO₃^– something like this:

Also read: How to draw Lewis structure of CH₂Cl₂ (4 steps)

#2 Show chemical bond

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

#3 Mark lone pairs

As calculated earlier, we have a total of 26 valence electrons. And in the above structure, we have already used six valence electrons. Hence, twenty valence electrons are remaining.

Two valence electrons represent one lone pair. So twenty valence electrons = ten lone pairs.

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.

So the Lewis structure of ClO₃^– 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.

Now calculate the formal charge and check the stability of the above structure.

Also read: How to draw Lewis structure of PCl₅ (4 steps)

#4 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 = 2
Bonding electrons = 6

Formal charge = 7 – 2 – ½ (6) = +2

• For each oxygen atom

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

Formal charge = 6 – 6 – ½ (2) = -1

Mention the formal charges of atoms on the structure. So the Lewis structure of ClO₃^– 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 C₂H₆ (3 steps)

#5 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 convert one lone pair from the two oxygen atoms to make a new bond with the chlorine atom. And then, the Lewis structure of ClO₃^– 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 = 2
Bonding electrons = 10

Formal charge = 7 – 2 – ½ (10) = 0

• For left oxygen and right oxygen atom

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

Formal charge = 6 – 4 – ½ (4) = 0

• For top oxygen atom

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

Formal charge = 6 – 6 – ½ (2) = -1

Mention the formal charges of atoms on the structure. So the Lewis structure of ClO₃^– looks something like this:

In the above structure, you can see that the formal charges of atoms are closer to zero. Therefore, this is the most stable Lewis structure of ClO₃^–.

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

Now ClO₃^– is an ion having a negative (-1) charge, so draw brackets around the above Lewis structure and mention that charge on the top right corner. And then, the Lewis structure of ClO₃^– looks something like this:

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Related

• Lewis structure of CH₂Cl₂
• Lewis structure of PCl₅
• Lewis structure of C₂H₆
• Lewis structure of CHCl₃
• Lewis structure of H₂

External video

• ClO3- Lewis Structure – How to Draw the Lewis Structure for ClO3- (Chlorate Ion) – Wayne Breslyn

External links

• Lewis Structure of ClO3- (Chlorate ion) – Chemistry School
• ClO3- Lewis Structure in 6 Steps (With Images) – Pediabay
• ClO3- Lewis Structure, Geometry – Kemicalinfo
• ClO3- lewis structure, molecular geometry, bond angle, hybridization – Topblogtenz
• Lewis Structure, Molecular Geometry, Hybridization & Shape – Geometry of Molecules
• ClO3- Lewis Structure, Molecular Geometry, Hybridization, and Polarity – Techiescientist
• draw the lewis structure for chlorate ClO3- – Chegg
• Asking to find the lewis bonding structure and formal charges on ClO3-(chlorate ion) that follows octet rule – Reddit
• Lewis Dot of the Chlorate Ion ClO3- – Kent’s Chemistry
• Formal Charge of Chlorate (ClO3-) – Chemistry Learner
• Chemical Bonding: ClO3- Lewis Structure – The Geoexchange
• Draw all possible resonance structures for the chlorate ion, ClO3-? – Pearson
• In the Lewis structure of the chlorate ion, ClO3-, how many lone pairs of electrons does the chlorine atom have? – Studocu
• What is the Lewis dot diagram for CLO3? – Quora
• Lewis structure of perchlorate ion – AceOrganicChem
• What is the Lewis structure for ClO3? – Homework.Study.com
• The Lewis structure for the chlorate ion, ClO3 – Numerade
• The Lewis structure for a chlorate ion – Bartleby
• Draw the Lewis structure for chlorate (ClO3-). For this structure, give each atom an octet and do not include a formal charge – OneClass
• Does a chlorate ion have resonance structures? – Socratic
• Based on formal charges, draw the most preferred Lewis structure for the chlorate ion, ClO3- – Brainly
• Draw a Lewis structure for ClO3-, being sure to show lone pairs and any formal charges – Course Hero
• Why does ClO3- only have 2 double bonds instead of 3? – Wyzant
• Why is chlorine the central atom in a chlorate ion – Physics Forums
• Chlorate ion Lewis Structure | Science, Chemistry – ShowMe