So you have seen the above image by now, right?
Let me explain the above image in short.
N3- (azide ion) lewis structure has three Nitrogen atoms (N). There are 2 double bonds between each Nitrogen atom (N). There are 2 lone pairs on both the outer Nitrogen atoms. There is a -1 formal charge on one of the outer Nitrogen atoms (N).
If you haven’t understood anything from the above image of N3- (azide ion) lewis structure, then just stick with me and you will get the detailed step by step explanation on drawing a lewis structure of N3- ion.
So let’s move to the steps of drawing the lewis structure of N3- ion.
Steps of drawing N3- lewis structure
Step 1: Find the total valence electrons in N3- ion
In order to find the total valence electrons in N3- (azide ion) ion, first of all you should know the valence electrons present in a single nitrogen atom.
(Valence electrons are the electrons that are present in the outermost orbit of any atom.)
Here, I’ll tell you how you can easily find the valence electrons of nitrogen using a periodic table.
Total valence electrons in N3- ion
→ Valence electrons given by nitrogen atom:
You can see the 5 valence electrons present in the nitrogen atom as shown in the above image.
Total valence electrons in N3- ion = valence electrons given by 3 nitrogen atoms + 1 more electron is added due to 1 negative charge = 5(3) + 1 = 16.
Step 2: Select the central atom
For selecting the center atom, you have to remember that the atom which is less electronegative remains at the center.
Now here the given molecule is N3. All the three atoms are same, so you can select any of the atoms as a center atom.
Step 3: Connect each atoms by putting an electron pair between them
Now in the N3 molecule, you have to put the electron pairs between all three nitrogen atoms (N).
This indicates that all three nitrogen (N) atoms are chemically bonded with each other in the N3 molecule.
Step 4: Make the outer atoms stable
Now in this step, you have to check the stability of the outer atoms.
Here in the sketch of N3 molecule, you can see that the outer atoms are nitrogen atoms only.
These outer nitrogen atoms are forming an octet and hence they are stable.
Also, in step 1 we have calculated the total number of valence electrons present in the N3- ion.
The N3- ion has a total 16 valence electrons and all these valence electrons are used in the above sketch.
Hence there are no remaining electron pairs to be kept on the central atom.
So now let’s proceed to the next step.
Step 5: Check the octet on the central atom. If it does not have octet, then shift the lone pair to form a double bond or triple bond.
In this step, you have to check whether the central Nitrogen atom (N) is stable or not.
In order to check the stability of the central nitrogen (N) atom, we have to check whether it is forming an octet or not.
Unfortunately, the central nitrogen atom is not forming an octet here. Nitrogen has only 4 electrons and it is unstable.
Now to make this nitrogen atom stable, you have to shift the electron pair from the outer nitrogen atom so that the central nitrogen atom can have 8 electrons (i.e octet).
But after shifting one electron pair, the central nitrogen atom is still not forming an octet as it has only 6 electrons.
So again we have to shift one more electron pair from the other nitrogen atom.
After shifting this electron pair, the central nitrogen atom will get 2 more electrons and thus its total electrons will become 8.
You can see from the above picture that the central nitrogen atom is forming an octet.
And hence this nitrogen atom is stable.
Now let’s proceed to the final step to check whether the lewis structure of N3 is stable or not.
Step 6: Check the stability of lewis structure
Now you have come to the final step in which you have to check the stability of lewis structure of N3.
The stability of lewis structure can be checked by using a concept of formal charge.
In short, now you have to find the formal charge on all the nitrogen (N) atoms present in the N3 molecule.
For calculating the formal charge, you have to use the following formula;
Formal charge = Valence electrons – (Bonding electrons)/2 – Nonbonding electrons
For central Nitrogen (N) atom:
Valence electrons = 5 (because nitrogen is in group 15)
Bonding electrons = 8
Nonbonding electrons = 0
For outer Nitrogen (N) atoms:
Valence electrons = 5 (because nitrogen is in group 15)
Bonding electrons = 4
Nonbonding electrons = 4
From the above calculations of formal charge, you can see that the central nitrogen (N) atom has -1 charge and the outer nitrogen atoms has -1 charges.
So let’s keep these charges on the respective atoms in the N3 molecule.
The +1 and -1 charge from the above sketch gets canceled and the only -1 charge remains in the above sketch, which gives -1 formal charge on the N3 molecule.
This overall -1 charge on the N3 molecule is represented in the image given below.
In the above lewis dot structure of N3- ion, you can also represent each bonding electron pair (:) as a single bond (|). By doing so, you will get the following lewis structure of N3- ion.
I hope you have completely understood all the above steps.
For more practice and better understanding, you can try other lewis structures listed below.
Try (or at least See) these lewis structures for better understanding:
|BH3 lewis structure
|C2H6 lewis structure
|COCl2 lewis structure
|BrF5 lewis structure
|NCl3 lewis structure
|CHCl3 lewis structure
Jay is an educator and has helped more than 100,000 students in their studies by providing simple and easy explanations on different science-related topics. He is a founder of Pediabay and is passionate about helping students through his easily digestible explanations.
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