# How are Lewis dot diagrams used to represent ions?

Let's take a simple example. We start with the neutral species ${H}_{3} C - X$, and make the lithium reagent.
${H}_{3} C - X + 2 L i \rightarrow {H}_{3} C - L i + L i X$
The methyl group in methyl lithium is formally anionic, which means that the $L i$ nucleus has a formal positive charge. The methyl carbanion FORMALLY has 7 electrons associated with it; 2 of these are inner core; 3 of the valence electrons of C are involved in the $C - H$ bonds (the other electron comes from the hydrogen!), and the remaining 2 valence electrons are assigned to the carbon. Since the carbon FORMALLY has 7 electrons, it has a formal negative charge, which balances the formal positive charge on lithium metal.