Lewis Structure Rules, Library Learning Links

Drawing Lewis Structures, a 2D representation of the covalent bonding between electrons in molecular compounds, can be accomplished in several different ways. Many methods are generalized and are simpler to use.

One method requires that you simply add up the valence electrons of elements in the compound and rearrange the electrons in pairs and as bonded pairs around each atom (such that each atom has eight electrons in the orbit of its nucleus).

When you arrange the electrons so that they share orbits with adjacent atoms,  one electron will be in the orbits of two atoms. If you had 18 total valence electrons in a compound of 3 atoms, at most, you could have 6 electrons per atom. But since each electron can be shared with another atom (the same orbit), the 18 electrons can be arranged such that each atom with have 8 electrons in it valence orbit. I

References:


UCLA, http://www.chem.ucla.edu/harding/lewisdots.html
UC Davis, ChemWiki: http://chemwiki.ucdavis.edu/Theoretical_Chemistry/Chemical_Bonding/Lewis_Theory_of_Bonding/Lewis_Structures

University of Maine, Lewis Dot Structure Rules, http://chemistry.umeche.maine.edu/CHY251/therules.html