Directory of Chem Help ASAP videos. Using the formula to calculate the formal charge on hydrogen we obtain. Calculating No3 Formal Charges Calculating Formal Charges For No3 Teaching Chemistry Chemistry Classroom Science Chemistry FC Formal Charge on Atom. . A step-by-step description on how to calculate formal charges. The formal charge on an atom in a molecule or ion is equal to the total number of valence electrons in the free atom minus the. You can calculate the formal charge of any atom with the help of the equation below. The formal charges when added. Formal charge Valence Electrons Sticks Dots. Formula to Calculate the Formal Charge. FC V LP 05BE Where. Formal charge exists because of deficiencies in the configuration of an atom that participates in the compound formation. Formal charge valence electrons nonbonding electrons 12 bonding electrons B Bonding electrons total electrons shared in.