Difference Between Sulfide and Sulfite

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Sulfur, the Latin word for brimstone, is a naturally occurring element. Used in matches, gunpowder and medicines, sulfur along with many other elements, is used to create a number of ions, or charged molecules. Sulfide and sulfite are two ions formed from sulfur. While the two have similarities, many differences exist between them.


Sulfur, an element with the atomic symbol “S,” has been in existence for centuries. It is a nonmetal, meaning it appears on the far right side of the periodic table. Its atomic number is sixteen, meaning sulfur atoms have 16 protons and electrons. At room temperature, sulfur appears as a yellow solid. Sulfur’s most common isotopes are S-32, S-33, S-34, S-35, and S-36. Of these isotopes, only S-35 is radioactive. Its half-life, or time it takes half a sample’s atoms to decay into another element, is 87.2 days.

Ions and Ionic Bonds

Ions are molecules that have been either positively or negatively charged. Atoms with an excess amount of protons become positively charged, while atoms with extra electrons become negatively charged. Ions that are oppositely charged become attracted to one another and form an ionic bond. During an ionic bond, the metal, ions formed from elements on the far left of the periodic table, share an electron with a nonmetal. Sulfite and sulfide are two kinds of ions with sulfur.


A sulfide ion is composed of a lone sulfur atom. Its charge is negative two, giving sulfides this formula: S^2-. Sulfide ions are extremely basic. One well-known ionic compound with a sulfide ion is H_2S. The infamous rotten-egg smell often associated with sulfur originates from this compound. Sulfide compounds are fairly soluble. Many compounds such as PbS, CuS, and HgS are insoluble in acidic and basic solutions. Other such as CoS, FeS, and MnS are only soluble in bases.


Being an ion, sulfite, like sulfide, has a negative charge. However, the distinguishing factor between sulfide and sulfite is their molecular make ups. Besides one sulfur atom, sulfites have three oxygen atoms. This addition causes the creation of bonds in the ion, another feature sulfide ions do not have. However, sulfite and sulfide are similar in ways. Sulfite ions, like sulfide, have a negative two charge. Sulfite ions have this formula: SO_3^2-. Sulfite ions are regularly used as a preservative in wines. They can be found naturally in acid rain, the result of the interactions between water and sulfur dioxide.


About the Author

Charles Alex Miller began writing professionally in 2010. He currently writes for various websites, specializing in the sciences. He is a full-time employee in the chemicals and environmental sciences industry.

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