Lewis Structure of NO3- (With 6 Simple Steps to Draw!) (2024)

Lewis structure of NO3- ion (nitrate ion) contains one double bond and two single bonds between the Nitrogen (N) atom and Oxygen (O) atoms. The Nitrogen atom (N) is at the center and it is surrounded by 3 Oxygen atoms (O).

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 NO3- ion).

6 Steps to Draw the Lewis Structure of NO3-

Step #1: Calculate the total number of valence electrons

Here, the given ion is NO3^–. In order to draw the lewis structure of NO3^– ion, first of all you have to find the total number of valence electrons present in the NO3^– ion.
(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 NO3^– ion

• 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 Oxygen:

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

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

Hence in a NO3^– ion,

Valence electrons given by Nitrogen (N) atom = 5
Valence electrons given by each Oxygen (O) atom = 6
Electron due to -1 charge, 1 more electron is added
So, total number of Valence electrons in NO₃^– molecule = 5 + 6(3) + 1 = 24

Step #2: Select the center atom

While selecting the center 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 NO3- ion, 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 remaining 3 oxygen atoms will surround it.

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

Now in the above sketch of NO3, put the two electrons (i.e electron pair) between each nitrogen atom and oxygen atom to represent a chemical bond between them.

These pairs of electrons present between the Nitrogen (N) and Oxygen (O) atoms form a chemical bond, which bonds the nitrogen and oxygen atoms with each other in a NO3- ion.

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 NO3^– ion, the outer atoms are oxygen atoms.

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

Now, you can see in the above image that both the oxygen atoms form an octet.

Also, all the 24 valence electrons of NO3- ion (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 NO₃^– ion.

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 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 and the nitrogen atom is stable.

Step #6: Check the formal charge

Now, you have come to the final step and here you have to check the formal charge on NO3- ion.

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

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

• For Nitrogen:
  Valence electrons = 5 (as it is in group 15)
  Nonbonding electrons = 0
  Bonding electrons = 8

• For double bonded Oxygen:
  Valence electron = 6 (as it is in group 16)
  Nonbonding electrons = 4
  Bonding electrons = 4

• For single bonded Oxygen:
  Valence electron = 6 (as it is in group 16)
  Nonbonding electrons = 6
  Bonding electrons = 2

Let’s keep these charges on the atoms in the above lewis structure of NO3^– ion.

As you can see in the above sketch, the pair of positive and negative charges gets canceled. Thus there is only one -ve charge left on the oxygen atom, which indicates the -1 formal charge on the NO3 molecule.

Hence, the above lewis structure of NO3- ion is the stable lewis structure.

Each electron pair (:) in the lewis dot structure of NO3- ion represents the single bond ( | ). So the above lewis dot structure of NO3- ion can also be represented as shown below.

Related lewis structures for your practice:
Lewis structure of O3
Lewis structure of C2H2
Lewis structure of CH2O
Lewis structure of SO3
Lewis structure of C2H4

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