ABSTRACT
Lewis structures are pictorial representations, not exact theoretical analyses, of the role of all valence electrons in a covalent molecule. The Lewis structure for an individual atom shows all valence electrons as dots around the symbol of the atom. The generally accepted method is to show the electrons as pairs or to show them symmetrically distributed around the symbol, especially when indicating bonding in molecules. A covalent bond is a shared pair of electrons between two atoms. The shared electron pair can most simply be described as occupying a region of space formed by orbital overlap of one atomic orbital from each of the two atoms forming the bond. Covalent bonds can most often be considered as being formed by a contribution of one electron from each of the two atoms involved in the bond formation. Under this condition, each covalent bond adds one additional electron to each of the bonding atom’s outer bonding valence shell.
