How can I write the formulas of these compounds?

Sulfide, everything about it.

Any of three classes of chemical compounds containing the element sulfur. The three classes of sulfides include inorganic sulfides, organic sulfides (sometimes called thioethers), and phosphine sulfides. Inorganic sulfides are ionic compounds containing the negatively charged sulfide ion, S2−; these compounds may be regarded as salts of the very weak acid hydrogen sulfide. Organic sulfides [...]more →