What is the Charge on Acetate ion (C2H3O2 or CH3COO)?

The Charge of Acetate ion (or C2H3O2 or CH3COO) is 1-.

But the question is how can you find the charge on Acetate ion (or C2H3O2 or CH3COO)?

Well there are 2 methods by which you can find the charge of Acetate ion (or C2H3O2 or CH3COO).

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 Acetate ion (or C2H3O2 or CH3COO) can be found out by looking at what it is bonded to.

So let’s take some examples of compounds that contain C₂H₃O₂ (or CH₃COO); like CH₃COOH, CH₃COONa, etc.

Example 1: CH₃COOH
In CH₃COOH, the CH₃COO is bonded to Hydrogen (H).
You know that the ionic charge of H is 1+.
So you can easily say that the charge of CH₃COO should be 1-, then only it will get canceled out.
Hence the charge of CH₃COO in CH₃COOH is 1-.

Example 2: CH₃COONa
In CH₃COONa, the CH₃COO is bonded to Sodium (Na).
And again, you know that the ionic charge of Na is 1+.
So here also you can easily say that the charge of CH₃COO should be 1-, then only it will get canceled out.
Hence the charge of CH₃COO in CH₃COONa is 1-.

As seen from the above examples,
The charge of CH₃COO is 1-.

In this way, you can easily find the charge of CH₃COO 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 CH₃COO (Acetate ion), you should know the Lewis dot structure of CH₃COO (Acetate ion).

Here is the lewis structure of CH₃COO.

Now using the above lewis structure of CH₃COO, you have to find the formal charge on each atom that is present in the CH₃COO 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 CH₃COO from the image given below.

So now let’s calculate the formal charge on each individual atom present in CH₃COO.

Formal charge on Carbon atom:
Valence electrons = 4 (as it is in group 14 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 = 4 – 0 – (8/2) = 0

So the formal charge on carbon atom is 0.

Formal charge on Hydrogen atom:
Valence electron = 1 (as it is in group 1 on periodic table) ^[2]
Nonbonding electrons = 0
Bonding electrons = 2

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

Formal charge on Hydrogen = Valence electrons – Nonbonding electrons – (Bonding electrons)/2 = 1 – 0 – (2/2) = 0

So the formal charge on hydrogen atom is 0.

Formal charge on double bonded Oxygen atom:
Valence electron = 6 (as it is in group 16 on periodic table) ^[3]
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 CH₃COO (Acetate ion) has 1- charge.

I hope you have understood the above calculations of CH₃COO (Acetate ion). But for your tests, you don’t need to remember the entire calculations. You should just try to remember that CH₃COO has 1- charge.

Check out some other related topics for your practice.

Related topics:
Charge on NO2 (Nitrite ion)
Charge on CO (Carbon monoxide)
Charge of Barium (Ba)
Charge of Fluorine (F)
Charge of Lithium (Li)