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

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

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

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

Lewis structure of HOCN has a triple bond between the Carbon-Nitrogen atom and a single bond between Carbon-Oxygen atom and Oxygen-Hydrogen atom. The Carbon atom (C) is at the center and it is surrounded by Nitrogen atom and O-H group. The Oxygen atom has 2 lone pairs and the Nitrogen atom has 1 lone pair.

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 HOCN).

6 Steps to Draw the Lewis Structure of HOCN

Step #1: Calculate the total number of valence electrons

Here, the given molecule is HOCN. In order to draw the lewis structure of HOCN, first of all you have to find the total number of valence electrons present in the HOCN 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 HOCN

• For Hydrogen: 

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

Hence, the valence electron present in hydrogen is 1 (see below image).

• For Oxygen:

Oxygen is a group 16 element on the periodic table. ^[2]

Hence, the valence electron present in oxygen is 6 (see below image).

• For Carbon:

Carbon is a group 14 element on the periodic table. ^[3]

Hence, the valence electrons present in carbon is 4 (see below image).

• For Nitrogen:

Nitrogen is a group 15 element on the periodic table. ^[4]

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

Hence in a HOCN molecule, 

Valence electron given by Hydrogen (H) atom = 1
Valence electrons given by Oxygen (O) atom = 6
Valence electrons given by Carbon (C) atom = 4
Valence electrons given by Nitrogen (N) atom = 5
So, total number of Valence electrons in HOCN molecule = 1 + 6 + 4 + 5 = 16

Step #2: Select the center atom (H is always outside)

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). ^[5]

Here in the HOCN molecule, if we compare the hydrogen (H) atom, oxygen atom (O), carbon atom (C)  and nitrogen atom (N), then hydrogen is less electronegative than oxygen, carbon and nitrogen. But as per the rule, we have to keep hydrogen outside.

So, carbon (which is less electronegative than oxygen and nitrogen) should be placed in the center and the nitrogen atom as well as OH group will surround it.

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

Now in the above sketch of HOCN molecule, put the two electrons (i.e electron pair) between the atoms to represent a chemical bond between them.

These pairs of electrons present between the atoms form a chemical bond, which bonds these atoms with each other in a HOCN 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 HOCN, the outer atoms are hydrogen atom, nitrogen atom as well as oxygen atom.

Hydrogen already has a duplet (see below image).

So now, you have to complete the octet on oxygen atom and nitrogen atom (because oxygen and nitrogen require 8 electrons to have a complete outer shell).

Now, you can see in the above image that the oxygen atom and nitrogen atom forms an octet.

Also, all the 16 valence electrons of HOCN molecule (as calculated in step #1) are used in the above structure. So there are no remaining electron pairs.

Hence there is no change in the above sketch of HOCN.

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 carbon) has an octet or not. 

In simple words, we have to check whether the central carbon (C) atom has 8 electrons or not.

As you can see from the above image, the central atom (i.e carbon) has only 4 electrons. So it does not fulfill the octet rule.

Now, in order to fulfill the octet of carbon atom, we have to move the electron pair from the outer atom to form a double bond.

Now the question is, from which atom should we move the electron pair?
From nitrogen? or
From oxygen? or
Both?

Well, we should move the electron from the atom which is less electronegative. Because the less electronegative atom has more tendency to lose the electrons.

Here, nitrogen is less electronegative than oxygen. Hence we should move electron pair from nitrogen. 

Still, the octet of carbon atom is not fulfilled as it has only 6 electrons.

So again moving the electron pair from nitrogen atom only, we will get the following structure.

Now you can see from the above image that the central atom (i.e carbon), is having 8 electrons. So it fulfills the octet rule.

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 Hydrogen atom (H), Oxygen atom (O), Carbon atom (C) as well as Nitrogen atom (N).

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

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

• For Hydrogen:
  Valence electron = 1 (as it is in group 1)
  Nonbonding electrons = 0
  Bonding electrons = 2
• For Oxygen:
  Valence electrons = 6 (as it is in group 16)
  Nonbonding electrons = 4
  Bonding electrons = 4
• For Carbon:
  Valence electron = 4 (as it is in group 14)
  Nonbonding electrons = 0
  Bonding electrons = 8
• For Nitrogen:
  Valence electron = 5 (as it is in group 15)
  Nonbonding electrons = 2
  Bonding electrons = 6

Formal charge	=	Valence electrons	–	Nonbonding electrons	–	(Bonding electrons)/2
H	=	1	–	0	–	2/2	=	0
O	=	6	–	4	–	4/2	=	0
C	=	4	–	0	–	8/2	=	0
N	=	5	–	2	–	6/2	=	0

So you can see above that the formal charges on all the atoms are “zero”.

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

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

Related lewis structures for your practice:
Lewis Structure of NHF2
Lewis Structure of BrCN
Lewis Structure of BeI2
Lewis Structure of CHBr3
Lewis Structure of SiCl2Br2 

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