•if the species is a cation,
subtract the charge of the cation from the total no. of
valence electrons.
•2.Count the total no. of atoms,
excluding H, in the molecule or ion. Multiply that no. by 8.
•Exception: multiply the no. of H’s by 2.
•This tells
you how many electrons you would need if you were putting 8
electrons around all atoms without any sharing of electrons
(and 2 around all H’s).