What is the Charge on IO3 (Iodate ion)? And Why?

The Charge of IO3 (Iodate ion) is 1-.

But the question is how can you find the charge on IO3 (iodate ion)?

Well there are 2 methods by which you can find the charge of IO3.

Lets dive right into these methods one by one.

You can also refer to the below video from which you will learn to find charge of any ion.

Method 1: By looking at what it is bonded to

The charge of IO3 (Iodate ion) can be found out by looking at what it is bonded to.

So let’s take some examples of compounds that contain IO₃; like Mg(IO₃)₂, HIO₃, etc.

Example 1: Mg(IO₃)₂
In Mg(IO₃)₂, the IO₃ is bonded to Magnesium (Mg).
You know that the ionic charge of Mg is 2+.
So you can easily say that the charge of IO₃ should be 1-, then only it will get canceled out.
Hence the charge of IO₃ in Mg(IO₃)₂ is 1-.

Example 2: HIO₃
In HIO₃, the IO₃ 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 IO₃ should be 1-, then only it will get canceled out.
Hence the charge of IO₃ in HIO₃ is 1-.

As seen from the above examples,
The charge of IO3 is 1-.

In this way, you can easily find the charge of IO3 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 IO3 (Iodate ion), you should know the Lewis dot structure of IO3 (Iodate ion).

Here is the lewis structure of IO3.

Now using the above lewis structure of IO3, you have to find the formal charge on each atom that is present in the IO3 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 IO3 from the image given below.

So now let’s calculate the formal charge on each individual atom present in IO3.

Formal charge on Iodine atom:
Valence electrons = 7 (as it is in group 17 on periodic table) ^[1]
Nonbonding electrons = 2
Bonding electrons = 10

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

Formal charge on Iodine = Valence electrons – Nonbonding electrons – (Bonding electrons)/2 = 7 – 2 – (10/2) = 0

So the formal charge on iodine atom is 0.

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 IO3.

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

This indicates that the IO3 (Iodate ion) has 1- charge.

I hope you have understood the above calculations of IO3 (Iodate ion). But for your tests, you don’t need to remember the entire calculations. You should just try to remember that IO3 has 1- charge.

Check out some other related topics for your practice.

Related topics:
Charge of Argon (Ar)
Charge of Scandium (Sc)
Charge of Platinum (Pt)
Charge on NO
Charge of Xenon (Xe)