Formal charge is the individual electric charges on the atoms in a given polyatomic molecule. These charges help in knowing if the given structure of the molecule is stable or not. One can calculate the formal charges for any given atom with the help of the following formula:
F.C = Valence electrons – Nonbonding electrons- Bonding electrons/2
FC = V – ( LP +.5 * BE)
Now that we know the formula let us look at the example of how to find out formal charges for individual atoms in a polyatomic molecule
Let us calculate the formal charges of SF4
| Atom | Total no. of valence electrons | Non-bonding electrons | Bonding electrons | Total charge |
| Sulphur (S) |
6 |
2 |
8 |
= 6-2-8/2
=6-2-4 =0 |
| Fluorine |
7 |
6 |
2 |
=7-6-2/2
=7-6-1 =0 |
Here in SF4 as all the Fluorine atoms are arranged symmetrically, they will have the same charges. And using the formula stated above, we found out that the total charges on both Sulphur and Fluorine atoms are zero.
Similarly, you can use this formula for other molecules and find out formal charges for individual atoms in the molecule. And to make it easy for you to do the calculations we have developed a Formal charge calculator for you, where you have to just enter the number of valence electrons, non-bonding electrons, and bonding electrons to find out the formal charge.
Sounds easy, right? Go ahead and try our formal charge calculator.
Do you know that a perfect diamond is made up of a single Carbon molecule? Chemistry is one of the most exciting subjects. And it might seem challenging, but it becomes the most fun and easy subject to learn if learned the correct way. The geometry of Molecules is a platform where we try to educate you about various chemistry concepts and find the answers you have been looking for. Come, let’s add fun to chemistry and enjoy this subject full of wonders!
