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 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 |
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