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Naming Ionic Compounds using Roman Numerals

(The Stock System of Naming)

 

The Stock System

History- The type of naming you will learn about is called the Stock system or Stock's system. It was designed by Alfred Stock (1876-1946), a German chemist and first published in 1919. In his own words, he considered the system to be "simple, clear, immediately intelligible, capable of the most general application."

In 1924, a German commission recommended Stock's system be adopted with some changes. For example, FeCl2,which would have been named iron(2)-chloride according to Stock's original idea, became iron(II) chloride in the revised proposal. In 1934, Stock approved of the Roman numerals, but felt it better to keep the hyphen and drop the parenthesis. This suggestion has not been followed, but the Stock system remains in use world-wide.

How do we name compounds when the cation of variable charge is involved?

Some elements have more then one oxidation number and when naming a compound these must be identified. Roman numerals are shown after the cation in parenthesis(  ) to indicate the oxidation number.

To determine what the oxidation number is, you must use the anion (negative ion) to determine what the positive oxidation number is.

Below you can see some of the elements with more than 1 oxidation number.

Example-  Pb(NO3)4   write the name  "lead nitrate". Since lead has more than one oxidation state we must figure out which lead we have. Since each nitrate (4 of them) has a 1- charge, the Pb must be 4+. So our roman numeral will be (IV).

Pb(NO3)4  is named "lead(IV)  nitrate"

Highlight to reveal names

Formula Name Formula Name
 FeCl2 iron (II) chloride SnCl4 tin (IV) chloride
CoBr3 cobalt (III) bromide  FeP iron (III) phosphide
MnO2 manganese (IV) oxide Hg2S mercury (I) sulfide
NiBr2 nickel (II) bromide  PbO lead (II) oxide
HgO mercury (II) oxide AuI gold (I) iodide
CuF2 copper (II) fluoride SnS2 tin (IV) sulfide
CuI copper (I) iodide FeBr3 iron (III) bromide
SnBr2 tin (II) bromide Cr2O3 chromium (III) oxide
Au3P gold (I) phosphide CoS cobalt (II) sulfide
Cr2S3 chromium (III) sulfide MnI2 manganese (II) iodide
NiBr nickel (I) bromide NiS nickel (II) sulfide
FeS iron (II) sulfide PbO2 lead (IV) oxide 
PbCl4 lead (IV) chloride Mn2O5 manganese (V) oxide

Naming Covalent Compounds   Naming Binary Ionic Compounds  Polyatomic Ions Naming with Polyatomic Ions  Naming with Roman Numerals  Formula Writing  Naming Acids

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