The Stock System

Since we are not using the ous-ic suffixes with the Stock system, the names of the ions are just the names of the elements themselves plus a Roman numeral  

Rule 4-In the Stock system the charges on metal atoms are indicated by Roman numerals written in parentheses after the name of the metal. 

Here are the names using the Stock system for the ions shown in the previous list  

Do not use the ous and /c suffixes and Roman numerals together use one or the other, but not both at the same time. 

An advantage of the Stock system is that you don t have to remember the Latin names of elements. However, you do have to understand Roman numerals. 

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EXAMPLE 13.13. Name the following according to the Stock system (a) FeCl, (6) U02S04, and (c) P4O10. (a) Iron(II) chloride, (b) dioxouranium(VI) sulfate, and (c) phosphorus(V) oxide. 

Name N02 and N204 using the Stock system. Explain why the older system using prefixes is still useful. 

To avoid the necessity of memorizing a separate name for each ion, we can use the Stock system. In the Stock system, the charge of the cation appears as a Roman numeral immediately after the name of the element. Using the Stock system, we write Fe2+ as the iron(II) ion, and Cu+ as the copper(I) ion. Other than the necessity of indicating the charges, there are no differences between the naming of transition metal compounds and other compounds of the metals. So while KC1 is potassium chloride, CuCl is copper(I) chloride. 

If the metal ion may exist in more than one oxidation state, this oxidation state should be listed, in Roman numerals, immediately after the name of the metal ion. The Roman numeral is enclosed in parentheses and is considered part of the same word, and not a separate grouping. If the metal occurs in only one oxidation state, no such indicator is used. This notation is the Stock system discussed earlier. 

Note According to the Stock system, metallic ions are named using Roman numerals. The Roman numeral shows the charge on the metal ion titanium(IV) W copper(l), Cu manganese(VIl), Mn +... 

This is the modem method and is called the Stock system. This name arises from the universal name of carbonate given to COs ". The name sodium bicarbonate is also accepted it is an older, historically used name. 

Modified Forms in Common Use. There are numerous situations in which the foregoing system does not meet all requirements. In the formation uf binary compounds, several elements exhibit more Ilian two states of oxidation. One method, recommended by the IUPAC, of handling these situations is the use of prefixes derived from Greek to indicate stoichiometric composition, e.g., titanium dichloride, TiCL and dinitrogen oxide (nitrous oxide) N 0. Other accepted methods ofindicating proportions of constituents are the Stock system (oxidation number) and the Ewens-Bassett (charge number) system. 

This Roman numeral method is known as the Stock system. An older nomenclature used the suffix -ous for the lower charge and -ic for the higher charge and is still used occasionally. 

The stock system may also be extended to those ternary compounds having anions with well-known names ... 

Naming Metals in Chemical Compounds The Stock System... 

Many of the common metals are transition elements that have more than one possible valence. For example, tin is able to form the ions Sn2+ and Sn4+, iron can form Fe2+ and Fe3+, and copper can form Cu+ and Cu2+. (The most common transition metals with more than one valence number are listed in Table 3.3.) The name of a compound must identify which ion is present in the compound. To do this, the element s name is used, followed by the valence in parentheses, written in Roman numerals. Therefore, Sn4+ is tin(IV), Fe3+ is iron(III), and Cu2+ is copper(II). This naming method is called the Stock system after Alfred Stock, a German chemist who first used it. Some examples of Stock system names are listed in Table 3.6. 

In a method that predates the Stock system, two different endings are used to distinguish the valences of metals. The ending -ic is used to represent the larger valence number. The ending -ous is used to represent the smaller valence number. Thus, the ions Sn2+ and Sn4+ are named stannous ion and stannic ion. To use this system, you need to know the Latin name of an element. For example, the two ions of lead are the plumbous and plumbic ions. See Table 3.6 for more examples. 

To name a binary compound containing metal and a non-metal, write the name of the metal first and the name of the non-metal second. For example, a compound that contains potassium as the cation and bromine as the anion is called potassium bromide. Be sure to indicate the valence if necessary, using the Stock system. For example, a compound that contains Pb2+ and oxygen is called lead(II) oxide. 

To indicate that a binary compound is made up of two non-metals, a prefix is usually added to both non-metals in the compound. This prefix indicates the number of atoms of each element in one molecule or formula unit of the compound. For example, P205 is named diphosphorus pen-toxide. Alternatively, the Stock System may be used, and P205 can be named phosphorus (V) oxide. AsBr3 is named phosphorus tribromide. 

Naming ions of metals that form ions of more than one charge requires distinguishing between the possibilities. For example, iron forms Fe and Fe ions. We cannot call both of these iron ion because no one would know which of the two we meant. For monatomic cations of variable type, the charge in the form of a Roman numeral is attached to the element s name to indicate which ion we are talking about. For example, Fe is called iron(II) ion and Fe is called iron(lll) ion. This system of nomenclature is called the Stock system. 

The Stock system name—vanadium(II) ion—is easy. To use the classical system, we must know the answers to at least three questions (1) What is the charge on the other monatomic ion of vanadium (2) Is the Latin name for vanadium used in the classical system (3) If the Latin name is used, what is that name The Stock system was invented to make naming easier. 

Name the following ions by the Stock system, using Table 6.2 if necessary ... 

In Chapter 6, we learned how to name cations. In the Stock system, the charges on monatomic ions were used to distinguish between different ions of the same element. For example, Cu and Cu are named copper ion and copper(ll) ion, respectively. The Roman numeral actually represents the oxidation number, not the charge on the ion. Of course, for monatomic ions, the charge is equal to the oxidation number, and thus we used the charge to determine which Roman numeral to use. By using oxidation numbers, however, we can extend our compound-naming ability to include compounds other than those of monatomic ions. For example, Hg2 is called the mercury(I) ion because the oxidation number of each mercury atom is +1. 

Oxidation numbers are used in the Stock system for naming compounds. Positive oxidation numbers are denoted as Roman numerals in parentheses in the names of the compounds the numbers of atoms or ions can be deduced from the oxidation numbers. (In contrast, the subscripts in formulas give the numbers of atoms or ions, from which the oxidation numbers may be deduced.) (Section 16.2). 

In Chap. 6 we placed Roman numerals at the ends of names of metals to distinguish the charges on monatomic cations. It is really the oxidation number that is in parentheses. This nomenclature system is called the Stock system. For monatomic ions, the oxidation number is equal to the charge. For other cations, again the oxidation number is used in the name. For example, Hg2 + is named mercury(I) ion. Its charge is 24- the oxidation number of each atom is 4-1. Oxidation numbers are also used for other cations, such as dioxovanadium(V) ion, V02". The prefix 0x0- stands for oxygen. Oxidation numbers can be used with nonmetal-nonmetal compounds, as in sulfur(VI) oxide for SO3, but the older system using prefixes (Table 6-2) is still used more often. 

EXAMPLE 14.13. Name the following according to the Stock system (a) NiCh, (b) UO2SO4, and (c) P2O5. 

Rule 7. It was recognized that the Stock system had become firmly established. 

Rule 7. The Ewens-Bassett system of designating the charge on a coordination ion is accepted as an alternate to the Stock system for indicating the oxidation state of the central atom. 

How can you determine the formula unit for an ionic compound containing a polyatomic ion Chemists use a naming system called the Stock System, after the German chemist Alfred Stock. Let s consider the compound formed from the ammonium ion and the chloride ion. 

This is the Stock system of indicating oxidation state of the metal (and indirectly, charge on the complex). Stock, A. Z. Anacw. Chem. 1919, 27. 373.]... 

Comment. This rule is simply an extension of the Stock system to coordination compounds. 

This report was published in 1940, when work in the International Union was suspended because of the war, and could not therefore be thoroughly discussed and criticized before an international forum. In the following years, the Stock system became widespread, especially in Germany and the United States. 

From an international point of view, however, the Stock nomenclature suffers from the serious drawback that it is more national in character than the older nomenclature. This may be substantiated by giving the names of FeS04 in different languages according to the older nomenclature and the Stock system ... 

Accordingly, the failure of the Stock system is that it uses the national names of the elements and, in spoken language, the national numerals. In written language, the numerals will be designated by Roman figures, but even then the Stock nomenclature is much more national than the one hitherto used. The joint Scandinavian (Danish, Finnish, Norwegian, and Swedish) nomenclature committee wrote on this matter to the International Union of Chemistry ... 

All of the examples used here involve elements with only one possible oxidation state. When we are required to name compounds that contain elements with more than one oxidation state, we use the stock system, which uses Roman numerals to indicate the oxidation number of the less electronegative element. We can usually determine the oxidation number of the less electronegative element by considering the rules for oxidation numbers presented in Lesson 5-1. It would probably be a good idea to review those rules before you try to follow these next examples. 

When the ternary ionic compound that we are trying to name contains a cation (positive ion) with multiple oxidation states, we still need to employ the stock system. For example, if we were asked to name the compound with the formula Cu(N03)2, we would determine that the oxidation number of the copper must be +2, because there are two nitrate ions, each with a charge of -1, and +2 + 2(-l) = 0. This would give us the name copper (II) nitrate for this compound. 

Following are several more examples of compounds and their proper names. Look at each example, and see if you understand why the stock system is used for some compounds and not for others. Remember The stock system is only used when you have a cation (or an atom with an apparent positive charge, in the case of molecular compounds) with more than one possible oxidation number. 

B. In order to write the balanced chemical reaction, we need to write the chemical formulas properly. The stock system tells us that the oxidation number for the iron, as in iron (III) chloride, will be +3. We look up any of the oxidation numbers that we don t know, and find this information ... 

These empirical formulas could be named diphosphorus pentoxide and diphosphorus trioxide. The names according to the Stock system are given below with the formulas of the actual compounds. 

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