Monatomic cation , nomenclature

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. 

Stock system (6.2, 16.2) The nomenclature system for inorganic compounds in which the oxidation state (or charge for a monatomic cation) is represented as a Roman numeral in the name of the compound, stoichiometry (10.1) The determination of how much a reactant can produce or how much of a product can be produced from a given quantity of another substance in a reaction. 

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. 

If there is more than one monatomic cation of an element, Rule 1 is not sufficient. The Stock system of nomenclature names the cations after the element, as in Rule 1, but follows this by a Roman numeral in parentheses denoting the charge on the ion. Example Fe is called iron(II) ion and Fe is called iron(III) ion. ... 

Many ionic componnds are binary compounds, or compounds formed from just two elements. For binary componnds the first element named is the metal cation, followed by the nonmetallic anion. Thus NaCl is sodium chloride. The anion is named by taking the first part of the element name (chlorine) and adding -ide. Potassium bromide (KBr), zinc iodide (Znl2), and aluminum oxide (AI2O3) are also binary componnds. Table 2.2 shows the -ide nomenclature of some common monatomic anions according to their positions in the periodic table. 

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