Ionic compounds their names

D.23 The names of some compounds of hydrogen are exceptions to the usual rules of nomenclature. Look up the following compounds, write their names, and identify them as ionic or molecular (a) LiAlH4 (b) NaH. 

The following sections describe five types of reactions that you d do well to recognize (notice how their names tell you what happens in each reaction). By recognizing the patterns of these five types of reactions, you can often predict reaction products when given only a set of reactants. (Note Figuring out the formulas of products often requires you to apply knowledge about how ionic and molecular compounds are put together. To review these concepts, see Chapters 5 and 6.)... 

D.4 The following ionic compounds are commonly found in laboratories. Write their modern names. 

Hydrates Some ionic compounds incorporate a fixed number of water molecules into their formula unit. The compound that contains the water is called a hydrate, and removal of the water affords the anhydrous salt. Compounds that have a strong tendency to absorb water are called hygroscopic. To name a hydrate, you simply name the ions and then add the appendage hydrate, along with a multiplier to indicate the number of water molecules in the formula. 

B. When two ionic compounds are in solution, a precipitation reaction should be considered. We can determine from their names that the two reactants are the ionic compounds Ca(N03)2 and U2SO4. The compounds are present in aqueous solution as their four component ions Ca2+, NCh-, Li+, and S042-. 

The word nomenclature simply means naming. You have already seen some chemical formulas such as NaCl, H20, and H2S04. There are many times when having names for chemicals is more convenient than having their formulas. Chemical naming falls into two main groups that for ionic compounds formed of positive and negative ions, and that for nonionic compounds. 

In writing formulas for ionic compounds from their names, we must remember the rules from Chapter 5. Be sure to balance the number of positive and negative charges The charges on the cations are implied for some cations (the constant type) and stated explicitly in the name for the others. The charge on a monatomic anion is equal to the group number minus 8 (see Section 5.2). 

We have not yet considered ionic compounds that contain polyatomic ions. For example, the compound ammonium nitrate, NH4NO3, contains the polyatomic ions NH4+ and N03. Polyatomic ions are assigned special names that must be memorized to name the compounds containing them. The most important polyatomic ions and their names are listed in Table 2.5. 

Naming ionic compounds Chemical nomenclature is a systematic way of naming compounds. Now that you are famihar with writing chemical formulas, you will use the following general rules in naming ionic compounds when their formulas are known. 

This diagram summarizes how to name ionic compounds from their formulas. 

Figure 8-8 reviews the steps used in naming ionic compounds if the formula is known. Naming ionic compounds is important in communicating the cation and anion present in a crystalhne solid or aqueous solution. How might you change the diagram to help you write the formulas for ionic compounds if you know their names ... 

Common names of some molecular compounds How frequently have you drunk an icy, cold glass of dihydrogen monoxide Quite frequently, hut you probably didn t call it that. You called it by its more common name, which is water. Remember from Chapter 8 that many ionic compounds have common names in addition to their scientific ones. Baking soda is sodium hydrogen carbonate and common table salt is sodium chloride. Many covalent compounds also have both common and scientific names. 

The names of some common ions appear in Table 2-3. You will need to know the names and formulas of these frequently encountered ions. They can be used to write the formulas and names of many ionic compounds. We write the formula of an ionic compound by adjusting the relative numbers of positive and negative ions so their total charges cancel (i.e., add to zero). The name of an ionic compound is formed by giving the names of the ions, with the positive ion named first. 

Ionic compounds are composed of cations and anions. The cation is always named first. Naming of the cation depends on whether the ion is monatomic. If not, special names are given, such as ammonium for and mercury(I) ion or mercurous ion for Hg, . If the cation is monatomic, the name depends on whether the element forms more than one positive ion in its compound. For example, sodium forms only one positive ion in all its compounds, NaT Iron forms two positive ions, Fe " and Fe, Cations of elements that form only one type of ion in all their compounds need not be further identified in the name. Cations of metals that occur with two or more different charges must be further identified. For... 

Describe the general structure of molecular and ionic compounds. (Sections 3.3 and 3.5) Convert between the names of compounds and their chemical formulas. (Section 5.3)... 

Although many compounds are molecular (as presented in Chapter 2), a very large number are best described as ionic, those composed of ions. In this chapter, the focus is on the formulas and names of ionic compounds. Nearly all ionic compounds are composed of both metals and nonmetals. Remember that metals have a great tendency to lose electrons in chemical reactions to form positive ions (cations), while nonmetals, in their reaction with metals, have a great tendency to gain electrons to form negative ions (anions). These ions of opposite charge combine to form ionic compounds. 

Each category of metals requires a different scheme for naming their compounds. You start by learning to name ionic compounds involving metals that only form only a single cation. 

In Section 2.5 we learned that ionic compounds are made up of cations (positive ions) and anions (negative ions). With the important exception of the ammonium ion, NH4, all cations of interest to us are derived from metal atoms. Metal cations take their names from the elements. For example ... 

Names of ionic compounds are derived from the names of their ions. The name of the cation appears first, followed by the name of the anion. In the Stock system for naming an ion (the systematic name), a Roman numeral indicates the charge of the cation. In the older common nomenclature system, the suffix -ous indicates the lower of the ionic charges, and the suffix -ic indicates the higher ionic charge. 

Some common monatomic cations and anions and their names are given in Table 2.3. The rules for naming binary ionic compounds are illustrated by the following examples ... 

As shown in Example 2.5, when a metal ion is present that forms more than one type of cation, the charge on the metal ion must be determined by balancing the positive and negative charges of the compound. To do this you must be able to recognize the common cations and anions and know their charges (see Tables 2.3 and 2.5). The procedure for naming binary ionic compounds is summarized in Fig. 2.20. 

Many molecular compounds have common names, but they also have scientific names that reveal their composition. To write the formulas and names of molecules, you will use processes similar to those described in Chapter 7 for ionic compounds. 

Determining the Names of Ionic Compounds from Their Formulas... 

The bonding between the atoms within polyatomic ions is just like the bonding within molecular compounds (Section 5.3), but the group of atoms has either more or fewer electrons than protons and therefore has an overall charge. Compounds that contain polyatomic ions are ionic, and their formulas are written by the same procedure described for binary ionic compounds. The only difference is that the polyatomic ion formula is enclosed in parentheses when more than one such ion is present. For example, the formula of aluminum nitrate is Al(NOg)g. The compounds are also named in the same manner as binary ionic compounds, with the... 

---