A stepbystep explanation of how to draw the ClO3 Lewis Structure (Chlorate Ion).

The ClO3 Lewis structure is a good structure to help you understand why calculating formal charges is important. There are two resonance structures for ClO3. The first structure you come up with might work in terms of filling the octets of each atom but you should check the formal charges for ClO3 since Chlorine (Cl) is in Period Three on the Periodic Table and can hold more than eight valence electrons.

For the ClO3 Lewis structure the total number of valence electrons (found on the periodic table) for the ClO3 molecule. In the Lewis structure of ClO3 structure there are a total of 26 valence electrons. ClO3 is also called Chlorate ion.

Once we know how many valence electrons there are in ClO3 we can distribute them around the central atom with the goal of filling the outer shells of each atom. Only use the number of available valence electrons we calculated earlier.

Also note that you should put the ClO3 Lewis structure in brackets with a negative sign on the outside to show that it is an ion with a negative one charge.

Steps to Write Lewis Structure for compounds like ClO3
1. Find the total valence electrons for the ClO3 molecule.
2. Put the least electronegative atom in the center. Note: Hydrogen (H) always goes outside.
3. Put two electrons between atoms to form a chemical bond.
4. Complete octets on outside atoms.
5. If central atom does not have an octet, move electrons from outer atoms to form double or triple bonds.

Lewis Resources
• Lewis Structures Made Simple:    • How to Draw Lewis Structures: Five Ea...  
• More practice:    • Lewis Dot Structure Practice Problems...  
• Counting Valence Electrons:    • Finding the Number of Valence Electro...  
• Calculating Formal Charge:    • Formal Charges: Calculating Formal Ch...  
• Exceptions to the Octet Rule:    • Exceptions to the Octet Rule  

Lewis Structures are important to learn because they help us understand how atoms and electrons are arranged in a molecule, such as Chlorate ion. This can help us determine the molecular geometry, how the molecule might react with other molecules, and some of the physical properties of the molecule (like boiling point and surface tension).

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