Naming compounds containing polyatomic ions

A polyatomic ion is an ion that contains two or more elements. Compounds containing polyatomic ions are composed of three or more elements and usually consist of one or more cations combined with a negative polyatomic ion. In general, naming compounds containing polyatomic ions is similar to naming binary compounds. The cation is named first, followed by the name for the negative polyatomic ion. 

Rules for Naming Compounds Containing Polyatomic Ions 

TABLE 6.6 Names, Formulas, and Charges of Some Common Polyatomic Ions 

Name Formula Charge Name Formula Charge 

Only four of the common negatively charged polyatomic ions do not use the ate-ite system. These exceptions are hydroxide (OH ), hydrogen sulfide (HS ), peroxide (02 ), 

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To learn to name compounds containing polyatomic ions... 

SAMPLE PROBLEM 6.6 Naming Compounds Containing Polyatomic Ions... 

Ionic compounds containing polyatomic ions (Section 2.8) are named in the same way as binary ionic compounds First the cation is identified and then the anion. For example, Ba(N03)2 is called barium nitrate because Ba2+ is the cation and the N03 polyatomic anion has the name nitrate. Unfortunately, there is no systematic way of naming the polyatomic ions themselves, so it s necessary to memorize the names, formulas, and charges of the most common ones listed in Table 2.3. The ammonium ion (NH4+) is the only cation on the list all the others are anions. 

Some compounds contain polyatomic ions that behave much like monatomic anions. Compounds that contain these ions are called pseudobinary ionic compounds. The prefix pseudo- means false these compounds are named as though they were binary compounds. The common examples of such polyatomic anions are the hydroxide ion, OH , and the cyanide ion, CN. The ammonium ion, NH4+, is the common cation that behaves like a simple metal cation. 

Naming ionic compounds containing polyatomic ions follows rules similar to those for naming binary compounds. 

Write correct formulas for ionic compounds containing representative metals and polyatomic ions, and correctly name binary covalent compounds and compounds containing polyatomic ions. (Section 4.10)... 

The formulas and names of some common polyatomic ions are given in I Table 4.7. From this information, the formulas and names for compounds containing polyatomic ions can be written. The rules are essentially the same as those used earlier for binary ionic compounds. In the formulas, the metal (or ammonium ion) is written first, the positive and... 

Compounds containing polyatomic ions are named in the same manner as binary ionic compounds. The name of the cation is given first, followed by the name of the anion. For example, the two compounds formed with silver by the nitrate and nitrite anions are named silver nitrate, AgN03, and silver nitrite, A 02, respectively. When multiples of a polyatomic ion are present in a compound, the formula for the polyatomic ion is enclosed in parentheses. 

When naming ionic compounds containing polyatomic ions, we write the positive ion, usually a metal, first, and then we write the name of the polyatomic ion. It is important that you learn to recognize the polyatomic ion in the formula and name it correctly. As with other ionic compounds, no prefixes are used. 

When naming compounds containing species not on these lists, it may help to find a chemical species on the list from the same family or a polyatomic ion that is similar. 

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. 

If the acid is a ternary acid, and it contains both chlorine and oxygen, move on to Rule 3. If the acid is any other ternary compound, delete the word hydrogen completely, and simply look at the name of the polyatomic ion that it contains. If the polyatomic ion ends in ate, change the ending to ic. If the polyatomic ion ends in ite, change the ending to ous. Add acid to the end of the name. 

You can identify other names as representing ionic compounds by recognizing that they contain the names of common polyatomic ions. For example, ammonium chloride and iron(III) hydroxide are both ionic compounds. Many of the polyatomic ions that you will be expected to recognize end in -ate, so this ending tells you that the name represents an ionic compound. Copper(II) sulfate is an ionic compound. 

Ionic compounds that contain polyatomic ions are named in the same way used to name binary ionic compounds. Attention must be paid as to whether the cation is a metal that forms a single cation or multiple cations, and the name of the polyatomic ion is that given in the table. Note how these six ionic compounds are named ... 

Correctly name the following ionic compounds that contain polyatomic ions. 

Naming ionic compounds that contain polyatomic ions is very similar to naming binary ionic compounds. For example, the compound NaOH is called sodium hydroxide, because it contains the Na+ (sodium) cation and the OH (hydroxide) anion. To name these compounds, you must... 

How is naming compounds that contain polyatomic ions similar to naming binary ionic compounds How is it different ... 

When the compound contains a polyatomic ion, simply name the cation followed by the name of the polyatomic ion. 

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