Formal Charge Formula: Definitions, Examples, Significance, Fun Facts, Importance, Why it Exists

Formal Charge Formula Overview

An atom in a covalently bound molecule is given a charge called a formal charge. Without taking into account relative electronegativity, it is believed that the chemical bonds are dispersed evenly among the atoms. The formal charge of an ion or an atom of a polyatomic molecule is the difference between the valence electron of an atom of a polyatomic molecule in the state of the element and the allocated number of electrons in the atom with Lewis structure. 

Also Read: ILATE Rule

What is a Formal Charge?

In chemistry, a formal charge (F.C. or q*) is the hypothetical charge attributed to an atom in a molecule under the covalent perspective of chemical bonding, assuming that electrons in all chemical bonds are shared equally between atoms regardless of relative electronegativity. The formal charge is defined as the difference between an atom's number of valence electrons in a neutral free state and the number allocated to that atom in a Lewis structure. 

Definition of Formal Charge 

The difference between the valence electron of an atom in the elemental state and the number of electrons allocated to that atom in Lewis structure is called the formal charge over that atom in a polyatomic molecule or ion.

Read more about the Lewis Base Examples.

Example of Formal Charge 

The proton is an unbonded, unpaired hydrogen atom with a formal charge of 1+. The hydride ion is a hydrogen atom with two electrons attached to it, no bonds, and a formal charge of one. A hydrogen atom with one unpaired electron, no bonds, and a formal charge of zero is known as a hydrogen radical.

Significance of Formal Charge Formula

The following are some of the significance of the formal charge formula-

1. Molecule Structure: A molecule should have a formal charge of zero in order to have the best stable state due to the lowest energy. 
2. Reactivity: A molecule's behavior throughout a process is dictated by its formal charge. An atom with a negative formal charge will be a nucleophile, or a producer of electrons in a process, whereas an atom with a positive formal charge will be an electrophile, or more likely to accept electrons.
3. Resonance: It is challenging for the formal charge to identify a molecule's preferred structure when several molecules have comparable but different molecular structures. The resonance structure can be useful if the molecules have similar atom configurations but differing bond arrangements.

Fun Facts about Formal Charge Formula

1. In organic chemistry, a formal charge is required to display a complete and exact Lewis-Kekulé structure. The same cannot be said for inorganic chemistry. 
2. The structural modification with the least amount of charge is the best. 
3. Because of the discrepancies in formal charge and oxidation state, Slater's valence bond theory and Mulliken's molecular orbital theory are now extensively used and far more accurate.

Read more about the F Shape Formula and Orbital Velocity Formula.

Importance of Formal Charge Formula

The following are the importance of formal charge formula-

1. The formal charge is a theoretical idea that can be beneficial when analyzing the molecule in great detail. 
2. It does not imply that the molecule has any true charge separation. 
3. This notion, as well as understanding 'what is a formal charge,' is critical.
4. The formal charge is critical in determining the lowest energy configuration for a particular molecule among various alternative Lewis structures. 
5. As a result, calculating formal charges becomes critical.
6. Knowing the lowest energy structure is essential for determining the principal product of a reaction. 
7. This information may also be used to describe a variety of occurrences.
8. The structure with the least energy is generally the one with the least formal charge and the most evenly distributed actual charge. 
9. Aside from understanding what a formal charge is, we now understand its significance. 

Formal Charge Formula

It may be stated mathematically using the following formula-

Why Formal Charge Formula exist?

A formal charge exists as a result of flaws in the atomic configurations that contribute to the production of molecules. When more than one resonant structure is conceivable, it is the formal charge that makes a certain arrangement and configuration acceptable for a molecule.

Points to Remember

1. Formal charges exist only in covalent bonds.
2. It aids in determining the most stable configuration of a molecule as well as reactivity and electron mobility in resonance structures.
3. Lewis's framework underpins formal charges.
4. The formal charge does not take electronegativity into consideration; it calculates an atom's charge based on all covalent bonds exchanging electrons equally.
5. The most stable formal charge is one that is close to zero.