Formal Charge Calculator with steps

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A formal charge calculator is an online tool to predict the formal charge on an individual atom. A formal charge is a charge assigned to an atom in a molecule. It is a hypothetical charge, not representing the actual charge on the atom. A formal charge concept is very helpful in determining whether the structure is stable or not.

  • Lesser the formal charge(near zero) is preferable for a stable structure.
  • For instance, +2 formal charge structure is less stable than +1 formal charge.

Formal charge calculator

 
 

How to use a Formal charge calculator?

Before using, Formal charge calculator tool, you must know some basic terms that will help you to understand the concept of a formal charge.

The formula used to calculate formal charge –

⇒ Formal charge = (valence electrons – nonbonding electrons –   1/2 bonding electrons)

Formal charge formula

Where,

V = Valence electrons (outershell electrons of atom)

N = Non bonding electrons (also called lone pair electrons)

B = Bonding electrons (total electrons shared in bonds with another atom)

Now, in Four steps you can calculate the formal charge for the atoms. To understand that we have to take an example.

Let’s take the example of the NH3 molecule,

NH3 structure

This is the lewis structure of NH3, Let’s calculate the formal charge on the Nitrogen (N) atom of it.

Step 1 – Find the valence electron of the nitrogen atom.

The nitrogen atom belongs to the 5A group in the periodic table, hence, the number of valence electrons in the nitrogen atom is 5.

Also read:- 

Step 2 – Find the number of nonbonding electrons on the nitrogen atom

Nonbonding electrons also called lone pair electrons are represented as dots in the structure of molecules or atoms. They do not take part in the formation of bonds.

Note: 1 lone pair means 2 nonbonding electrons

find nonbonding electron of nitrogen to calculate the formal charge

So, the number of nonbonding electrons on the Nitrogen atom is 2.

Step 3 – Find the number of bonding electrons around the nitrogen atom

Bonding electrons are the number of electrons shared in bonds with other atoms. They are mostly represented as single, double, or triple bonds in the structure of a molecule.

Note: One single bond contains two bonding electrons.

find bonding electron of nitrogen to calculate the formal charge

So, the number of bonding electrons around the Nitrogen atom is 6.

Step 4 – Calculate the formal charge of the nitrogen atom

So, we have got the data for calculating the formal charge for nitrogen atoms.

 For nitrogen atom

⇒ Valence electrons of nitrogen = 5

⇒ Nonbonding electrons on nitrogen = 2

⇒ Bonding electrons around nitrogen (3 single bonds) = 6

Put these values in the Formal charge calculator and hit the calculate button.

formal charge on nitrogen atom in NH3 molecule

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How to calculate the Formal charge for Compounds?

Let’s say you have to find the overall formal charge for the compound. Let’s take an example of a CO2 compound. Before calculating the formal charge for CO2, first, you must draw the lewis structure for CO2.

For instance, the structure of CO2 is –

CO2 structure

Let’s find out the formal charge for the individual atom of the CO2 molecule.

Start with an oxygen atom –

⇒ The number of valence electrons in the oxygen atom is 6.

⇒ Nonbonding electrons of oxygen = 4

find nonbonding electron of oxygen to calculate the formal charge

⇒ Bonding electrons around oxygen (one double bond) = 4

find bonding electron of oxygen to calculate the formal charge

∴ (6 – 4 – 4/2) = 0 formal charge on the oxygen atom.

formal charge on oxygen atom in CO2 molecule

Now calculate the formal charge for the carbon atoms.

⇒ Valence electrons of carbon = 4

⇒ Nonbonding electrons on carbon = 0

⇒ Bonding electrons around carbon (two double bonds) = 8

find nonbonding and bonding electron of carbon to calculate the formal charge

∴ (4 – 0 – 8/2) = 0 formal charge on the carbon atom.

formal charge on carbon atom in CO2 molecule

So, Each atom (carbon and oxygen) in the CO2 structure gets a formal charge equal to zero.

Calculating overall formal charge in CO2 molecule

Therefore, the overall formal charge in CO2 is zero, and according to the concept of formal charge, this is the best and most stable structure of CO2.

So, that’s you can easily calculate the formal charge for any atom or molecule, or you can use our Formal charge calculator tool to get the answer quickly.

Formal charge is very neccessary to check the stability of lewis structures.

Also see, How to draw a lewis structure?

FAQ

How to use the Formal charge calculator tool?

To use the formal charge calculator tool, you must have three data of an atom.

  • Valence electron of the atom.
  • The number of nonbonding electrons on the atom.
  • The number of bonding electrons around an atom.

After that, fill the data in respective fields and hit the calculate button of the Formal charge calculator to get the answer.

Formal charge calculator

What is a formal charge and its formula?

A formal charge is a charge assigned to an atom in a molecule. It is a hypothetical charge, not representing the actual charge on the atom. The lesser the formal charge(near to zero) better is the stability of the structure.

The formula for the formal charge is –

formal charge concept

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