Simple Procedure for drawing Lewis Structures for the Azide ion N3- -#13

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 and #11. 

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

 Let us consider the case of azide ion (N₃^-). Azides are energy-rich molecules with many applications. Sodium azide (NaN₃), for example, is used as a preservative, mutagen, biocide and assay reagent. It has also been used as a component in the gas generators used to inflate certain automotive airbag safety systems, providing the source of nitrogen gas necessary to inflate the bag instantaneously. Organic azides are capable of a great diversity of organic reactions and are important components in Click Chemistry.

Step 1: Connect the atoms with single bonds

Fig. 1: Connecting the N atoms of the azide ion with single bonds according to step 1 of the method

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

Where n in this case is 3 since N₃^- consists of three atoms.

Where V = (5 + 5 + 5) – (-1) = 16  

Therefore, P = 6n + 2 – V = 6 * 3 + 2 – 16 = 4    Therefore,  there are 4 π electrons (pi electrons) in N₃^-

and that means that 2 double bonds or 1 triple bond must be added to the structure of Step 1.
 Step 3 & 4: The Lewis structures for N₃^- are as follows:

Figure 2: Lewis structures for N₃^- _.  Structure 1 is the most plausible since it has the smallest charge separation .