How to Memorize Ionic Compounds

By David Foulds
Jason Reed/Photodisc/Getty Images

Reciting the names of ionic compounds may seem a daunting task. However, there are a few simple rules you can use in memorizing the most commonly encountered ionic compounds in chemistry. An ionic compound has two parts: a positively charged cation and a negatively charged anion. By following rules for naming each part, you will find the process simple and easy.

Naming Cations

Determine if the cation has only one possible charge by looking at the periodic table. If so, the cation name is simply the name of the compound. For example: NaCl is sodium chloride and KOH is potassium hydroxide. The alkali metals most commonly encountered are sodium (Na), lithium (Li) and potassium (K). The most commonly encountered alkali earth metals are magnesium (Mg) and calcium (Ca). Other metals that have only one charge include aluminum (Al), zinc (Zn) and silver (Ag).

Determine if the cation is a transition metal. Some metals require a change of name: Pb = plumb, Fe = ferr, Cu = cupr, Sn = stan. You can remember these names by referring to their symbols.

Determine if the cation has two possible charges. If so, name cations with the lower charge with the suffix "-ous" and the higher charge with the suffix "-ic." For example, Cu+ is cuprous, Cu2+ is cupric. Fe2+ is ferrous, Fe3+ is ferric. Pb2+ is plumbus, Pb3+ is plumbic. Hg(2)2+ is mercurous, Hg2+ is mercuric. Sn2+ is stannous, Sn4+ is stannic.

Determine if the cation is hydrogen. If so, it is simply named "hydrogen." For example, H2S is hydrogen sulfide.

Naming Anions

Determine if the anion is a negatively charged single element. If so, then name it with the suffix -ide. For example: O = oxide, F = flouride, Cl = chloride, Br = bromide.

Determine if the anion is a polyatomic anion with oxygen. If so, use the suffix "-ate" for compounds with more oxygen, and -ite in compounds with less oxygen. For example: SO4 = sulfate, SO3 = sulfite, NO3 = nitrate, NO2 = nitrite.

Determine if the anion is -OH. If so, it is named hydroxide. For example: KOH is potassium hydroxide.

Determine if the anion is hydrogen. If so, it is named "hydride." For example: LiH is lithium hydride.

About the Author

David Foulds has been writing on media and science topics since 2005. He holds a B.S. in biology from UC Berkeley, an M.A. in media studies and is pursuing a dual master's degree in biology and English. Foulds also has extensive experience in film production and completed a year of medical school.