What is the Charge on NO3 (Nitrate ion)? And Why?

The Charge of NO3 (Nitrate ion) is 1-.

But the question is how can you find the charge on NO3 (nitrate ion)?

Well there are 2 methods by which you can find the charge of NO3.

Lets dive right into these methods one by one.

If you are a visual learner like me, then here is a short two minute video for you.

Method 1: By looking at what it is bonded to

The charge of NO3 (Nitrate ion) can be found out by looking at what it is bonded to.

So let’s take some examples of compounds that contain NO₃; like NaNO₃, HNO₃, KNO₃, etc.

Example 1: NaNO₃
In NaNO₃, the NO₃ is bonded to Sodium (Na).
You know that the ionic charge of Na is 1+.
So you can easily say that the charge of NO₃ should be 1-, then only it will get canceled out.
Hence the charge of NO₃ in NaNO₃ is 1-.

Example 2: HNO₃
In HNO₃, the NO₃ is bonded to Hydrogen (H).
And again, you know that the ionic charge of H is 1+.
So here also you can easily say that the charge of NO₃ should be 1-, then only it will get canceled out.
Hence the charge of NO₃ in HNO₃ is 1-.

As seen from the above examples,
The charge of NO3 is 1-.

In this way, you can easily find the charge of NO3 by looking at what it is bonded to.

Method 2: By calculating the formal charge using lewis structure

In order to calculate the formal charge on NO3 (Nitrate ion), you should know the Lewis dot structure of NO3 (Nitrate ion).

Here is the lewis structure of NO3.

Now using the above lewis structure of NO3, you have to find the formal charge on each atom that is present in the NO3 molecule.

For calculating the formal charge, you need to remember this formula;

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

You can see the bonding and nonbonding electrons of NO3 from the image given below.

So now let’s calculate the formal charge on each individual atom present in NO3.

Formal charge on Nitrogen atom:
Valence electrons = 5 (as it is in group 15 on periodic table) ^[1]
Nonbonding electrons = 0
Bonding electrons = 8

So according to the formula of formal charge, you will get;

Formal charge on Nitrogen = Valence electrons – Nonbonding electrons – (Bonding electrons)/2 = 5 – 0 – (8/2) = 1+

So the formal charge on nitrogen atom is 1+.

Formal charge on double bonded Oxygen atom:
Valence electron = 6 (as it is in group 16 on periodic table) ^[2]
Nonbonding electrons = 4
Bonding electrons = 4

So according to the formula of formal charge, you will get;

Formal charge on double bonded Oxygen = Valence electrons – Nonbonding electrons – (Bonding electrons)/2 = 6 – 4 – (4/2) = 0

So the formal charge on double bonded oxygen atom is 0.

Formal charge on single bonded Oxygen atom:
Valence electron = 6 (as it is in group 16 on periodic table)
Nonbonding electrons = 6
Bonding electrons = 2

So according to the formula of formal charge, you will get;

Formal charge on single bonded Oxygen = Valence electrons – Nonbonding electrons – (Bonding electrons)/2 = 6 – 6 – (2/2) = 1-

So the formal charge on single bonded oxygen atom is 1-.

Now let’s put all these charges on the lewis dot structure of NO3.

So there is overall 1- charge left on the entire molecule.

This indicates that the NO3 (Nitrate ion) has 1- charge.

I hope you have understood the above calculations of NO3 (Nitrate ion). But for your tests, you don’t need to remember the entire calculations. You should just try to remember that NO3 has 1- charge.

Check out some other related topics for your practice.

Related topics:
Charge on SO4 (Sulfate ion)
Charge of Iodine (I)
Charge on CO3 (Carbonate ion)
Charge of Beryllium (Be)
Charge of Sulfur (S)