Examples coming soon

No items found.

Calculations and examples

How to calculate formal change

Refresher: Each atom on the periodic table has a set number of valence electrons. The number of valence electrons increases across the periodic table. When atoms form covalent bonds, one pair of electrons is shared between the atoms for every single bond. Two pairs of electrons are shared in a double bond and three pairs are shared in a triple bond.

Definition of formal charge

Formal charge is the charge placed on each atom in a molecule, ignoring relative electronegativities. It is a result of the electrons associated with each atom in the molecule. Even if a molecule is overall neutral, a formal charge can be associated with the atoms in the molecule (which would add up to result in an overall zero charge). Knowing how electrons are distributed in a molecule and the formal charge helps us to predict how the molecule will react.


Equations


Examples






Main Takeaways

  • You can calculate formal charge by determining the amount of valence electrons an atom should have and subtracting the amount of electrons it has in the molecule of interest.
  • Each lone pair of electrons is two electrons that the atom has and each bond contributes one electron.
  • All of the formal charges should add up to the charge on the overall molecule.

--