A Recipe for Drawing Lewis Structures

• Determine the total number of valence electrons in the structure, adding or subtracting electrons from ions, as necessary.

• Determine the atom with the lowest electronegativity (other than hydrogen), this atom is generally the central atom in the structure. Hydrogen is virtually always a terminal atom.

• Distribute the other atoms around the central atom. Place an electron pair between each terminal atom and the central atom to form a single bond.

• Distribute the remaining valence electrons around the terminal atoms so that each has a complete octet.

• If valence electrons are still not used in the structure, place them around the central atom to complete its octet.

• If, after all the valence electrons are distributed, the central atom still lacks a complete octet, transform lone pairs on a terminal atom into a multiple bond.

• Check that formal charges are either zero, or are as low as possible.

• Check that only "acceptable" violations of the octet rule occur in the structure.