Simple Method for writing Lewis Structures – Lewis Structures of CF3NO -#16

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 and  #15.

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

Let us consider the case of trifluoronitrosomethane(CF₃NO) . It is used as a monomer (building block) for specialty rubbers (nitroso rubber in conjuction with tetrafluoroethylene) and as a military poison gas.  

Step 1: The central atom will be the C atom since it is the less electronegative. Connect the atoms with single bonds:

Fig. 1: Connect the atoms of  CF3NO with single bonds according to step 1 of the procedure

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 6 since CF₃NO consists of six atoms.

Where V = (7*3 + 4 + 5 + 6 ) = 36  

Therefore, P = 6n + 2 – V = 6 * 6 + 2 – 36 = 2   So, There are 2 π electrons in CF₃NO  

Therefore, 1 double bond must be added to the structure of Step 1. 

 Step 3 & 4: The Lewis structure for CF₃NO is as follows:

Figure 2: Lewis structures for CF₃NO. The only position that the double bond can be placed is between the N and O atom. There is an octet of electrons around each atom.