The Lewis structure of S2- is represented by the capital letter "S" that is surrounded by eight dots, including a "2-" superscript that indicates the charge of the ion. The dots denote the total valence electrons in the ion's outermost shell.
A Lewis structure, also referred to as a Lewis electron dot diagram, is a graphic depiction of an atom's total number of valence electrons. These electrons determine the chemical bonding properties of the atom.
For negatively charged atoms, such as the sulfide ion S2-, the typical number of valence electrons for a neutral sulfur atom, which is six, is increased by two for a total of eight electrons. In the Lewis structure for the sulfide ion, the eight dots that signify the valence electrons are normally arranged into two dots each on the left, right, top and bottom side of the chemical symbol for sulfur.