Starting with a structure indicating only atom connections (single bonds),
you can practice constructing a Lewis dot structure.
Just click on the atom or bond you wish to modify.
Nonzero formal charges are indicated for each atom in the structure
once the total number of electrons is correct.
A recommended procedure might be:
- Count the total number of valence electrons (N) needed to account for the atoms (based on the column of the atom in the periodic table) and charge (add one electrons for each negative charge; subtract one electron for each positive charge).
- Draw the framework with single bonds. Some knowledge of the way the atoms are connected may be required.
- Using lone pairs, complete octets around the noncentral atoms.
- Count the number of electrons depicted
(two for each bond and two for each lone pair).
If this number is less than N,
then add electrons to the central atom until the total
number of electrons depicted is N.
- If the octet rule is not satisfied for the central atom and lone-pair electrons are nearby, use those electrons to make double or triple bonds to the central atom.
- Check each atom to see if it has a formal charge. (Singly bonded oxygen will require a negative charge, for example.)