<P> An electron may form a part of the shell of two different atoms and cannot be said to belong to either one exclusively . </P> <P> Moreover, he proposed that an atom tended to form an ion by gaining or losing the number of electrons needed to complete a cube . Thus, Lewis structures show each atom in the structure of the molecule using its chemical symbol . Lines are drawn between atoms that are bonded to one another; occasionally, pairs of dots are used instead of lines . Excess electrons that form lone pairs are represented as pair of dots, and are placed next to the atoms on which they reside: </P> <P> To summarize his views on his new bonding model, Lewis states: </P> <P> Two atoms may conform to the rule of eight, or the octet rule, not only by the transfer of electrons from one atom to another, but also by sharing one or more pairs of electrons...Two electrons thus coupled together, when lying between two atomic centers, and held jointly in the shells of the two atoms, I have considered to be the chemical bond . We thus have a concrete picture of that physical entity, that "hook and eye" which is part of the creed of the organic chemist . </P>

What can be said about the concept of molecules