Lewis Structure of NI3 (With 6 Simple Steps to Draw!)

I’m super excited to teach you the lewis structure of NI3 in just 6 simple steps.

Infact, I’ve also given the step-by-step images for drawing the lewis dot structure of NI3 molecule.

So, if you are ready to go with these 6 simple steps, then let’s dive right into it!

Lewis structure of NI3 contains three single bonds between the Nitrogen (N) atom and each Iodine (I) atom. The Nitrogen atom (N) is at the center and it is surrounded by 3 Iodine atoms (I). The Nitrogen atom has 1 lone pair and all the three Iodine atoms have 3 lone pairs.

Let’s draw and understand this lewis dot structure step by step.

(Note: Take a pen and paper with you and try to draw this lewis structure along with me. I am sure you will definitely learn how to draw lewis structure of NI3).

6 Steps to Draw the Lewis Structure of NI3

Step #1: Calculate the total number of valence electrons

Here, the given molecule is NI3 (nitrogen triiodide). In order to draw the lewis structure of NI3, first of all you have to find the total number of valence electrons present in the NI3 molecule.
(Valence electrons are the number of electrons present in the outermost shell of an atom).

So, let’s calculate this first.

Calculation of valence electrons in NI3

• For Nitrogen:

Nitrogen is a group 15 element on the periodic table. ^[1]

Hence, the valence electrons present in nitrogen is 5 (see below image).

• For Iodine:

Iodine is a group 17 element on the periodic table. ^[2]

Hence, the valence electrons present in iodine is 7 (see below image).

Hence in a NI3 molecule, 

Valence electrons given by Nitrogen (N) atom = 5
Valence electrons given by each Iodine (I) atom = 7
So, total number of Valence electrons in NI3 molecule = 5 + 7(3) = 26

Step #2: Select the center atom

While selecting the atom, always put the least electronegative atom at the center. 

(Remember: Fluorine is the most electronegative element on the periodic table and the electronegativity decreases as we move right to left in the periodic table as well as top to bottom in the periodic table). ^[3]

Here in the NI3 molecule, if we compare the nitrogen atom (N) and iodine atom (I), then the nitrogen is less electronegative than iodine.

So, nitrogen should be placed in the center and the remaining 3 iodine atoms will surround it.

Step #3: Put two electrons between the atoms to represent a chemical bond

Now in the above sketch of NI3 molecule, put the two electrons (i.e electron pair) between each nitrogen atom and iodine atom to represent a chemical bond between them.

These pairs of electrons present between the Nitrogen (N) and Iodine (I) atoms form a chemical bond, which bonds the nitrogen and iodine atoms with each other in a NI3 molecule.

Step #4: Complete the octet (or duplet) on outside atoms. If the valence electrons are left, then put the valence electrons pair on the central atom

Don’t worry, I’ll explain!

In the Lewis structure of NI3, the outer atoms are iodine atoms.

So now, you have to complete the octet on these iodine atoms.

Now, you can see in the above image that all the iodine atoms form an octet.

Also, only 24 valence electrons of NI3 molecule are used in the above structure.

But there are total 26 valence electrons in NI3 molecule (as calculated in step #1).

So the number of electrons left to be kept on the central atom = 26 – 24 = 2.

So let’s keep these two electrons (i.e electron pair) on the central atom.

Now, let’s move to the next step.

Step #5: Check whether the central atom has octet or not. If it does not have an octet, then move the electron pair from the outer atom to form a double bond or triple bond

In this step, we have to check whether the central atom (i.e nitrogen) has an octet or not. 

In simple words, we have to check whether the central Nitrogen (N) atom is having 8 electrons or not.

As you can see from the above image, the central atom (i.e nitrogen), has 8 electrons. So it fulfills the octet rule and the nitrogen atom is stable.

Step #6: Final step – Check the stability of lewis structure by calculating the formal charge on each atom

Now, you have come to the final step and here you have to check the formal charge on nitrogen atom (N) as well as each iodine atom (I).

For that, you need to remember the formula of formal charge;

Formal charge = Valence electrons – Nonbonding electrons – (Bonding electrons)/2

• For Nitrogen:
  Valence electron = 5 (as it is in group 15)
  Nonbonding electrons = 2
  Bonding electrons = 6
• For Iodine:
  Valence electron = 7 (as it is in group 17)
  Nonbonding electrons = 6
  Bonding electrons = 2

Formal charge	=	Valence electrons	–	Nonbonding electrons	–	(Bonding electrons)/2
N	=	5	–	2	–	6/2	=	0
I	=	7	–	6	–	2/2	=	0

So you can see above that the formal charges on nitrogen as well as iodine are “zero”.

Hence, there will not be any change in the above structure and the above lewis structure of NI3 is the final stable structure only.

Each electron pair (:) in the lewis dot structure of NI3 represents the single bond ( | ). So the above lewis dot structure of NI3 can also be represented as shown below.

Related lewis structures for your practice:
Lewis structure of CH2F2
Lewis structure of CH3-
Lewis structure of I2
Lewis structure of ICl3
Lewis structure of NOF

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