Simple method for writing Lewis Structures: Chlorine Dioxide ClO2 - Ex.#19

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, #17 and #18.

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

Let us consider the case of chlorine dioxide (ClO₂). Chlorine dioxide is used mainly for bleaching of wood pulp, for bleaching of flour and for the disinfection of municipal drinking water:

 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 3 since ClO₂ consists of three atoms.

Where V = (6 + 6 + 7 ) = 19  

Therefore, P = 6n + 2 – V = 6 * 3 + 2 – 19 = 1   So there is only 1 π electron in ClO₂ 

So the structure of Step 1 is the Lewis structure.

Electrons are placed around each atom so that the octet rule is obeyed. Since the number of valence electrons is odd the octet rule will not be obeyed in all the atoms.

Formal charges are assigned and equalized using resonance.

 

Step 3 & 4: The Lewis structure for ClO₂  is as follows:

Figure 1: Plausible Lewis structures for chlorine dioxide. Oxygen is more electronegative than chlorine so it can accommodate better the negative charge. Structure 3 has no formal charge.   The real molecule is a hybrid of the above Lewis structures