-ic -ous nomenclature

Question

I recently came across a practice problem in my textbook asking me to name a few compounds using -ic and -ous endings. The exact wording is:

Write the name of each of the following ionic substances, using -ous and -ic endings to indicate the charge of the cation.

The first one was $\ce{CoCl2}$. However, cobalt has more than just two oxidization states (3, 2, 0, and -1).

So if it is one of the states in the middle, how do I decide whether to use -ous or -ic

score 11 · Accepted Answer · answered Jul 31 '14 at 00:36

11

Cobalt may possibly have all those other oxidation states (and others too) for this nomenclature system, we only care about the two most common oxidation states in ionic compounds: $\ce{Co^{2+}}$ and $\ce{Co^{3+}}$. Cobalt(II) compounds would thus be named cobaltous and cobalt(III) compounds would be cobaltic. Which is yours?

answered Jul 31 '14 at 00:36

Ben Norris

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Chloride is -1 and it's Cl2 so Cobaltous. Thanks! – 735Tesla Jul 31 '14 at 00:38
-1 as in the charge, not your answer. That was really helpful! +1 – 735Tesla Jul 31 '14 at 00:38
Is there a reference you would recommend for finding the most common oxidization states? I can't find one in my book and online. – 735Tesla Jul 31 '14 at 01:59
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$\ce{Co^3+}$ oxidizes $\ce{Cl-}$. I know this from personal experience. – A.K. Aug 17 '18 at 00:25
Depending on its ligands Co3+ might oxidize Cl- is closer to the truth – Ian Bush Aug 17 '18 at 06:11

-ic -ous nomenclature

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