Sodium chloride nomenclature

Additive nomenclature1 is based on the combination of element names or roots of element names and/or ligand names. The simplest and oldest additive nomenclature is binary nomenclature that expresses two components, e.g. sodium chloride. The cationic or electropositive portion of the compound expressed in a binary name is the element name unchanged or a group name ending in -ium , and the anionic or electronegative portion of a compound expressed in the name ends in -ide, -ite or -ate. The proportions of cations and anions in neutral compounds are indicated by Stock numbers or simple or multiplicative prefixes (see Section 3.3.2). Additive nomenclature denotes composition. For examples see Table 1. 

When writing a chemical formula, you learned that you write the metal element first. Similarly, the metal comes first when naming a chemical compound. For example, sodium chloride is formed from the metal sodium and the non-metal chlorine. Think of other names you have seen in this chapter, such as beryllium chloride, calcium oxide, and aluminum oxide. In each case, the metal is first and the non-metal is second. In other words, the cation is first and the anion is second. This is just one of the rules in chemical nomenclature the system that is used in chemistry for naming compounds. 

Nomenclature of Salts. — Salts containing only two elements follow the rule for binary compounds, aiid hence end in -ide. This suffix is added to an abbreviated form of the name of the non-metal, e.g. chloride, bromide, duor-ide, etc. Notice that the prefix hydro- is omitted, and that the name of the metal precedes, c.g. sodium chloride, potassium bromide, calcium fluoride, etc. It will soon be shown experimentally that salts may be regarded as derived from... 

Muriatic acid and marine acid were synonymous terms for what is now called hydrochloric acid, thus signifying its relation to the sodium chloride contained in brine (Latin muria) or sea water (Latin mare). Both names were strongly criticized by H. Davy in a scathing paper entitled Some reflections on the nomenclature of oxymuriatic compounds in Phil. Trans. R. Soc. for 1811 To call a body which is not known to contain oxygen, and which cannot contain muriatic acid, oxymuriatic acid, is contrary to the principles of that nomenclature in which it is adopted and an alteration of it seems necessary to assist the progress of the discussion, and to diffuse just ideas on the subject. If the great discoverer of this substance (i.e. Scheele) had signified it by any simple name it would have been proper to have referred to it but... 

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. 

If the cation and anion exist in only one common charged form, there is no ambiguity between formula and name. Sodium chloride must be NaCl, and lithium sulfide must be Li2S, so that the sum of positive and negative charges is zero. With many elements, such as the transition metals, several ions of different charge may exist. Fe ", Fe + and Cu+, Cu + are two common examples. Clearly, an ambiguity exists if we use the name iron for both Fe + and Fe + or copper for both Cu" and Cu +. Two systems have been developed to avoid this problem the Stock system and the common nomenclature system. 

The Stock Oxidation-Number System. Stock sought to correct many nomenclature difficulties by introducing Roman numerals in parentheses to indicate the state(s) of oxidation, eg, titanium(II) chloride for TiCl2, iron(II) oxide for FeO, titanium(III) chloride for TiCl, iron(III) oxide for Fe203, titanium(IV) chloride for TiCl, and iron(II,III) oxide for Fe O. In this system, only the termination -ate is used for anions, followed by Roman numerals in parentheses. Examples are potassium manganate(IV) for K2Mn02, potassium tetrachloroplatinate(II) for K PtCl, and sodium hexacyanoferrate(III) for Na3Fe(CN)3. Thus a set of prefixes and terminations becomes uimecessary. 

The cations formed as shown by the half-reactions above are simply given the names of the metals that produced them, such as sodium for Na+ and calcium for Ca +. Since they consist of only one element, the name for each anion has an -ide ending, that is, hP", nitride CP , oxide S , sulfide H , hydride F, fluoride and Cl , chloride. An advantage in the nomenclature of ionic compounds is that it is not usually necessary to use prefixes to specify the numbers of each kind of ion in a formula unit. This is because the charges on the ions determine the relative numbers of each, as shown by the examples in Table 4.3. 

In this symbol, three pieces of information are depicted. The center designates the species of interest (zinc). The subscript tells us what crystal site that species sits in (interstitial), while the superscript tells us the effective charge ( + l). The effective charge is relative to that of the site in the perfect lattice. For example, consider a crystal of NaCl. The sodium normally gives up a valence electron to chloride to form the ionic bonds in the lattice. However, if a calcium atom exists as a substitutional impurity in a sodium site, it may lose both its valence electrons. Its effective charge, relative to the sodium that would normally sit there, is then +1. The nomenclature for such an impurity would be written as Cajjja. ... 

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