Structural Representation of organic molecules

Before any of a molecule's chemistry can be discussed, it first has to be represented clearly on paper. A structural (or 'dash') formula does this most fully: every atom in the molecule is written out with its own symbol, and every covalent bond between two directly-bonded atoms is drawn as a single dash connecting them. For methane, CH4, this means drawing the central carbon symbol with four separate dashes radiating out to four separate H symbols. An electron-dot (Lewis) structure carries the same information in a different visual form: instead of a dash, every valence electron of every atom is drawn explicitly as a dot around that atom's symbol, and a shared covalent bond is shown as a PAIR of dots sitting between the two bonded atoms. In methane's electron-dot structure, each of the four C-H bonds is drawn as its own pair of dots between C and that particular H -- so overall carbon is surrounded by four such bonding pairs (eight dots), with no additional lone-pair dots left over on carbon, since methane's carbon uses every one of its four valence electrons in bonding. Because a full structural or electron-dot formula becomes unwieldy for anything beyond the smallest mo …