Lewis Electron Dot Structures - Simple Procedure for writing Lewis Structures of Chloric Acid (HClO3)

A simple procedure for writing Lewis structures is given in a previous article entitled “Lewis Structures and the Octet Rule”. Relevant worked examples were given in the following articles: Examples #1, #2, #3 , #4, #5, #6,  #7,  #8, #9, #10, #11, #12, #13, #14,  #15 and #16.

Another example  for writing Lewis structures following the above procedure is given bellow:

Let us consider the case of chloric acid (HClO₃):

 Step 1: Connect the atoms with single bonds. Chlorine is the central atom.

 Step 2:  Calculate the # of electrons in π bonds (multiple bonds) using  formula (1) in the article entitled “Lewis Structures and the Octet Rule”.:

 Where n in this case is 4 since HClO₃consists of 5 atoms but one of them is a hydrogen atom (remember n is the number of atoms in a molecule minus the hydrogen atoms).

Where V = (1 + 7 + 3*6 ) = 26  

Therefore, P = 6n + 2 – V = 6 * 4 + 2 – 26 = 0   and therefore  there are no π electrons in HClO₃  

So the structure of Step 1 is the Lewis structure.

Electrons are placed around each atom so that the octet rule is obeyed. Formal charges are assigned and equalized using resonance.

 Step 3 & 4: The Lewis structure for HClO₃  is as follows:

Figure 1: Lewis structures for chloric acid. Electron pairs are delocalized so that charge separation becomes minimal.