Formal Charge Calculator with steps
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.
- A lesser formal charge(near zero) is preferable for a stable structure.
- For instance, the +2 formal charge structure is less stable than the +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)
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,
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.
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
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.
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.
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Also, check –
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 –
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
⇒ Bonding electrons around oxygen (one double bond) = 4
∴ (6 – 4 – 4/2) = 0 formal charge on the oxygen atom.
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
∴ (4 – 0 – 8/2) = 0 formal charge on the carbon atom.
So, Each atom (carbon and oxygen) in the CO2 structure gets a formal charge equal to zero.
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 important to check the stability of lewis structures.
Also see, How to draw a lewis structure?
Check some examples of Formal charges
- SO3 formal charge
- CO2 formal charge
- HCN formal charge
- SO42- formal charge
- PO43- formal charge
- SO32- formal charge
- CN– formal charge
- SO2 formal charge
- O3 formal charge
- SCN– formal charge
- POCl3 formal charge
- NH3 formal charge
- CO formal charge
- H2O formal charge
- NH4+ formal charge
- H3O+ formal charge
- OH– formal charge
- HSO4– formal charge
- ClO– formal charge
- BH4– formal charge
- N3– formal charge
- H2SO4 formal charge
- NCO– formal charge
- NO3– formal charge
- NO2– formal charge
- ClO3– formal charge
- CH3 formal charge
How to use the Formal charge calculator tool?
To use the formal charge calculator tool, you must have three data of an atom.
After that, fill the data in respective fields and hit the calculate button of the Formal charge calculator to get the answer.
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 –
About the author
Vishal Goyal is the founder of Topblogtenz, a comprehensive resource for students seeking guidance and support in their chemistry studies. He holds a degree in B.Tech (Chemical Engineering) and has four years of experience as a chemistry tutor. The team at Topblogtenz includes experts like experienced researchers, professors, and educators, with the goal of making complex subjects like chemistry accessible and understandable for all. A passion for sharing knowledge and a love for chemistry and science drives the team behind the website. Let's connect through LinkedIn: https://www.linkedin.com/in/vishal-goyal-2926a122b/
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