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

Ready to learn how to draw the lewis structure of HNO?

Awesome!

Here, I have explained 6 simple steps to draw the lewis dot structure of HNO (along with images).

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

Lewis structure of HNO contains a double bond between the Nitrogen (N) & Oxygen (O) atom and a single bond between the Nitrogen (N) and Hydrogen (H) atom. The Nitrogen atom (N) is at the center and it is surrounded by Oxygen and Hydrogen atoms. The Nitrogen has 1 lone pair and the Oxygen has 2 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 HNO).

6 Steps to Draw the Lewis Structure of HNO

Step #1: Calculate the total number of valence electrons

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

• 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 Nitrogen:

Nitrogen is a group 15 element on the periodic table. ^[2]

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

• For Oxygen:

Oxygen is a group 16 element on the periodic table. ^[3]

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

Hence in a HNO molecule, 

Valence electrons given by Hydrogen (H) atom = 1
Valence electrons given by Nitrogen (N) atom = 5
Valence electrons given by Oxygen (O) atom = 6
So, total number of Valence electrons in HNO molecule = 1 + 5 + 6 = 12

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). ^[4]

Here in the HNO molecule, hydrogen (H) will always remain outside as per the rule. Now, if we compare the nitrogen atom (N) and oxygen atom (O), then nitrogen is less electronegative than oxygen.

So, nitrogen should be placed in the center and the oxygen atom will surround it.

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

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

These pairs of electrons present between the Hydrogen (H), Nitrogen (N) and Oxygen (O) atoms form a chemical bond, which bonds these atoms with each other in a HNO 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 HNO, the outer atoms are hydrogen atom and oxygen atom.

Hydrogen already has a duplet (see below image).

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

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

Also, only 10 valence electrons of HNO molecule are used in the above structure.

But there are total 12 valence electrons in HNO molecule (as calculated in step #1).

So the number of electrons left to be kept on the central atom = 12 – 10 = 2.

So let’s keep these two electrons (i.e 1 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 has 8 electrons or not.

As you can see from the above image, the central atom (i.e nitrogen) has only 6 electrons. So it does not fulfill the octet rule.

Now, in order to fulfill the octet of nitrogen atom, we have to move the electron pair from the outer atom (i.e oxygen atom) to form a double bond.

Now you can see from the above image that the central atom (i.e nitrogen), 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), nitrogen atom (N) as well as oxygen atom (O).

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

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

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

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

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

Related lewis structures for your practice:
Lewis structure of NI3
Lewis structure of CH2F2
Lewis structure of CH3-
Lewis structure of I2
Lewis structure of ICl3

---

Article by;