Naming Binary Molecular Compounds

Naming Binary Molecular Compounds /Cs Solvelt Cards HMDScience.com  

Sample Problem D a. Give the name for AS2O3. b. Write the formula for oxygen difluoride.  

Some covalent compounds are a network with no single molecules. 

Some covalent compounds do not consist of individual molecules. Instead, each atom is joined to aU its neighbors in a covalently bonded, three-dimensional network. There are no distinct units in these compounds, just as there are no such units in ionic compounds. The subscripts in a formula for a covalent-network compound indicate the smallest whole-number ratio of the atoms in the compound. Naming such compounds is similar to naming molecular compounds. Some common examples are given below. 

Acids are solutions of water and a special type of compound. 

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Naming binary molecular compounds requires using Greek prefixes to indicate the number of atoms of each element in the compound or molecule. Prefixes are given in Table 1.4. Prefixes precede each element to indicate the number of atoms in the molecular compound. The stem of the second element takes the ide suffix. The prefix mon is dropped for the initial element that is, if no prefix is given, it is assumed that the prefix is 1. Examples of molecular compounds are carbon dioxide (C02), carbon monoxide (CO), and dinitrogen tetroxide (N204). 

The anesthetic dinitrogen oxide (N2O), commonly known as nitrous oxide, is a covalently bonded compound. Because it contains only two different elements, it is a binary molecular compound. Binary molecular compounds are composed of two different nonmetals and do not contain metals or ions. Although many of these compounds have common names, they also have scientific names that reveal their composition. Use the following simple rules to name binary molecular compounds. 

Using the system of rules for naming binary molecular compounds, describe how you would name the molecule N2O4. 

Unlike ionic compounds, molecular compounds contain discrete molecular units. They are usually composed of nonmetallic elements (see Figure 2.8). Many molecular compounds are binary compounds. Naming binary molecular compounds is similar to naming binary ionic compounds. We place the name of the first element in the formula first, and the second element is named by adding -ide to the root of the element name. Some examples are... 

Specific rules are used when naming binary molecular compounds, binary acids, and oxyacids. 

Naming Binary Molecular Compounds Name the compound P2O5, which is used as a drying and dehydrating agent. 

You are given the formula for a compound. The formula contains the elements and the number of atoms of each element in one molecule of the compound. Because only two different elements are present and both are nonmetals, the compound can be named using the rules for naming binary molecular compounds. 

In naming binary molecular compounds, the first part of the name is simply that of the first element in the chemical formula, and the second part of the name is that of the second element with an -ide ending. Therefore, the name of HCl is hydrogen chloride. In most cases, however, it is necessary to have prefixes to designate the relative number of atoms in the molecular formula. These prefixes are the following ... 

Unlike ionic compounds, molecular compounds contain discrete molecular units. They are usually composed of nonmetallic elements (see Figure 0.9). Many molecular compounds are binary compounds. Naming binary molecular compounds is... 

Rules for Naming Binary Molecular Compounds Now let us look at the rules for naming binary molecular compounds by the prefix system. 

The rules for naming binary molecular compounds are sometimes confused with those for naming polyatomic oxyan-ions. The critical difference in the formulas of the two species is that ions have charges and molecules do not. NO2 is uncharged, and therefore it is a binary molecular compound. Its name is nitrogen dioxide. NO2 has a charge therefore it is an oxyanion. Its name is nitrite ion. 

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. 

The old system of naming binary molecular compounds uses prefixes. 

The prefix mono- is generally omitted for the first element. SO2, for example, is named sulfur dioxide, not monosulfur dioxide. Thus, the absence of a prefix for the first element usually means there is only one atom of that element present in the molecule. In addition, for ease of pronunciation, we usually eliminate the last letter of a prefix that ends in "o or a when naming an oxide. Thus, N2O5 is dinitrogen pentoxide, rather than dinitrogen pentaoxide. Sample Problem 2.4 gives you some practice naming binary molecular compounds from their formulas. 

State the rules for naming binary molecular compounds. 

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