Simple Method for writing Lewis Structures of Perchloric Acid HClO4 -Ex.#18

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, #16 and 17.

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

Let us consider the case of perchloric acid (HClO₄):

 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 5 since HClO₄consists of 6 atoms but one of them is a hydro gen atom (remember n is the number of atoms in a molecule minus the hydrogen atoms).

Where V = (1 + 7 + 4*6 ) = 32  

Therefore, P = 6n + 2 – V = 6 * 5 + 2 – 32 = 0     

So there are no π electrons in HClO₄  and therefore 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 HClO₄  is as follows:

Figure 1: Lewis structures for perchloric acid