Nomenclature binary molecular compounds

Chemical nomenclature is the systematic naming of compounds based on their formulas or structures. Rules are given for naming ionic compounds, binary molecular compounds, acids, and hydrates. 

The oxides of nitrogen are ideal for practicing the nomenclature of binary molecular compounds. 

In Section 1, we introduced the use of Roman numerals to denote ionic charges in the Stock system of naming ionic compounds. The Stock system is actually based on oxidation numbers, and it can be used as an alternative to the prefix system for naming binary molecular compounds. In the prefix system, for example, SO2 and SO3 are named sulfur dioxide and sulfur trioxide, respectively. Their names according to the Stock system are sulfur(IV) oxide and sulfur(VI) oxide. The international body that governs nomenclature has endorsed the Stock system, which is more practical for complicated compounds. Prefix-based names and Stock-system names are still used interchangeably for many simple compounds, however. 

Some compounds, namely molecular compounds, contain only nonmetals. Normally the compounds you need to name are binary compounds (containing only two elements). If you have highlighted the metalloids on your periodic table, everything to the right of the metalloids is a nonmetal. The following rules apply to both nonmetals and metalloids. The only nonmetal excluded from these nomenclature rules is hydrogen. 

In this section, we discuss the nomenclature of some simple inorganic compounds. We hrst look at the naming of ionic compounds. Then, we look at the naming of some simple molecular compounds, including binary molecnlar componnds (molecular compounds of two elements) and acids. Finally, we look at hydrates of ionic compounds. These substances contain water molecules in loose association with ionic compounds. 

Unlike ionic compounds, molecular compounds are composed of individual covalently bonded units, or molecules. Chemists use two nomenclature systems to name binary molecules. The newer system is the Stock system for naming molecular compounds, which requires an understanding of oxidation numbers. This system will be discussed in Section 2. 

Acids were first recognized as a specific class of compounds based on their properties in solutions of water. Consequently, in chemical nomenclature, the term acid usually refers to a solution in water of one of these special compounds rather than to the compound itself. For example, hydrochloric acid refers to a water solution of the molecular compound hydrogen chloride, HCl. Some common binary and oxyacids are listed in Figure 1.6. Figure 1.7 shows some common laboratory acids. 

Since this is the book s first look at nomenclature, we limit ourselves to molecular binary compounds, those made up of only two elements, both nonmetals. Other binary compounds are named in Chapter 4, after you learn more about ions. Let s start by naming four molecular binary compounds to get an idea how names are formed, and then follow this with some rules. 

Attempts have been made to systematize the nomenclature, and Herbstein, in his major work Crystalline Molecular Complexes and Compounds, gives a classification scheme for binary adducts made up of compounds A and B, which depend on the dominance of the A- A, B- B, and A- B interactions. 

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