Lewis Structure of ClO3- (Chlorate ion)

Lewis structure of ClO3- ion is drawn step by step in this tutorial. Total valence electrons of oxygen and chlorine atoms and negative charge are considered to draw the ClO3- lewis structure. When we drew the lewis structure, overall charge of the ion should be -1.

Lewis Structure of nitrite ion

ClO3- lewis structure

Now, we are going to learn, how to draw this lewis structure of ClO3- ion step by step.

Steps of drawing ClO3- lewis structure

Following steps are required to draw ClO3- lewis structure and they are explained in detail in this tutorial.

  1. Find total number of electrons of the valance shells of chlorine and oxygen atoms and including charge of the anion
  2. Total electrons pairs in valence shells
  3. Determine center atom from chlorine and oxygen atom
  4. Put lone pairs on atoms
  5. Stability of lewis structure - Check the stability and minimize charges on atoms by converting lone pairs to bonds to obtain the best structure.

Drawing correct lewis structure is important to draw resonance structures of ClO3-.

Total number of electrons of the valance shells of chlorine and oxygen atoms and charge of the anion

There are one chlorine atom and three oxygen atoms in the chlorate ion. Also there is a -1 charge on the ClO3- ion.

Chlorine and oxygen are located at 7 and 6 groups respectively in the periodic table. So chlorine has seven electrons in its valence shell. In oxygen atom, there are six electrons in its valence shell.

  • Total valence electrons given by chlorine atoms = 7*1 = 7

There are three oxygen atoms in ClO3- , Therefore

  • Total valence electrons given by oxygen atoms = 6 *3 = 18

Due to -1 charge, another electrons is added

  • Due to -1 charge, received electrons to valence electrons= 1

  • Total valence electrons = 7 + 18 + 1 = 26

Total valence electrons pairs

Total valance electrons pairs = σ bonds + π bonds + lone pairs at valence shells

Total electron pairs are determined by dividing the number total valence electrons by two. For, ClO3- there are 26 valence electrons, so total pairs of electrons are 13.

Center atom of ClO3- ion

To be the center atom, ability of having greater valance is important. Chlorine can show valence 7. But, oxygen's maximum valence is 2. Therefore chlorine has more chance to be the center atom (See the figure). So, now we can build a sketch of ClO3- ion.

Sketch of ClO3- ion

center atom of ClO3- and sketch-

Lone pairs on atoms

  • There are already three Cl-O bonds in the sketch. Therefore only ten valence electrons pairs are remaining to draw the rest of ion.
  • Next step is, marking those ten valence electrons pairs on outside atoms (oxygen atoms) as lone pairs. One oxygen atom will take three lone pairs following the octal rule (oxygen atoms cannot keep more than eight electrons in their valence shells). Therefore, nine electrons pairs are marked on three oxygen atoms. Now, one electrons pair (10-9) is remaining.
  • Then, remaining electron pair is marked on chlorine atom.
mark valence electrons on atoms in chlorate lews structure

Check the stability of drawn structure of ClO3- ion and reduce charges on atoms by converting lone pairs to bonds

Check charges on atoms and mark them as below. Charges are important to decide the best lewis structure of the ion.

mark charges of atoms ClO3- lewis structure

The drawn structure for ClO3- is not a stable structure because oxygen atoms and chlorine atoms have charges. Also, when charge of an atom is large, that structure become more unstable. When a molecule or ion has so many charges on atoms, that structure is not stable.

Now, we should try to minimize charges by converting lone pair or pairs which exist on oxygen atoms to bonds. So we convert one lone pair of one oxygen atom as a Cl-O bond as in the following figure.

reduce charges on atoms of ClO3-

Now there is a double bond between chlorine and one oxygen atom. There are also two single bonds (Cl-O) with chlorine atom and other two oxygen atoms.

But, there are still charges on atoms. If possible, we should reduce charges furthermore. Another lone pair on another oxygen atom is transferred as a Cl-O bond.

reduce charges to get best ClO3- lewis

Now, there are twelve electrons around chlorine atom. This is acceptable because chlorine can keep more than eight electrons chlorine has unfilled 3d orbits.

In new structure, charges of atoms are reduced furthermore. Now there is no any charge on two oxygen atoms. Also, charge of chlorine atom is reduced to zero. Now you understand this structure of ClO3- is more stable than previous structure due to less charges on atoms.

ClO3- Lewis structure

best ClO3- lewis structure


What is the shape around chlorine atom in ClO3- ion?

There are three σ bonds and a one lone pair around chlorine atom in lewis structure of ClO3- ion. Therefore, shape of ion is trigonal pyramidal.

How many charges in atoms of chlorate ion lewis structure?

Only one oxygen atom has a -1 charge. All other atoms do not have charges. Therefore, overall charge of chlorate ion is -1.

clo3 lewis structure

There is no molecule or ion as ClO3. The correct formula of chlorate ion is ClO3-.


Draw a Lewis structure for the chlorate ion, ClO3- in which all atoms satisfy, but do not exceed, the octet rule. Now draw a second structure that is the best structure based on formal charge considerations. In the Lewis structures that you’ve drawn, how many single and double bonds surround the central atom in each structure?

If you are going to protect octal rule and try to draw a lewis structure, you will get a structure which is very unstable due to charges in every atom (-1 charge on every oxygen atom and chlorine atom has +2 charge). Such structure cannot be considered as a stable structure.

You can find a more stable structure by forming two double betweens chlorine atom and two oxygen atom as mentioned in this tutorial.

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