{"id":237,"date":"2018-03-19T16:07:27","date_gmt":"2018-03-19T16:07:27","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-orgbiochemistry\/chapter\/ionic-nomenclature\/"},"modified":"2018-08-08T16:54:38","modified_gmt":"2018-08-08T16:54:38","slug":"ionic-nomenclature","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-monroecc-orgbiochemistry\/chapter\/ionic-nomenclature\/","title":{"raw":"3.4 Ionic Nomenclature","rendered":"3.4 Ionic Nomenclature"},"content":{"raw":"
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Learning Objectives<\/h3>\r\n1. Use the rules for naming ionic compounds.\r\n\r\n<\/div>\r\n<\/div>\r\n
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Naming Ions<\/h2>\r\nNaming the Cation<\/strong>\r\n

The name of a monatomic cation is simply the name of the element followed by the word ion<\/em>. Thus, Na+<\/sup> is the sodium ion, Al3+<\/sup> is the aluminum ion, Ca2+<\/sup> is the calcium ion, and so forth.\u00a0 Metals ions from Group 1 always have a 1+<\/sup> charge, metals ions from Group 2 always have a 2+ <\/sup>charge, the only aluminum ion is 3+<\/sup>, zinc ions are\u00a0 2+<\/sup>, and silver ions are 1+<\/sup>.\u00a0 These are the fixed-charge metals<\/strong>.\u00a0 The names for fixed-charge metal ions must never<\/em> be given a Roman numeral.<\/p>\r\n

Metals that can have several different charges as ions are referred to as variable-charge metals.\u00a0 <\/strong>Almost all transition metals plus the metals under the staircase are variable-charge metals. Iron, for example, can form two different cations, each of which, when combined with the same anion, makes a different compound with unique physical and chemical properties.\u00a0 For example, FeCl2<\/sub> and FeCl3<\/sub> differ in density, melting point, solubility, and color.\u00a0 Thus, we need a different name for each iron ion to distinguish Fe2+<\/sup> from Fe3+<\/sup>. The same issue arises for all of the variable-charge metals.<\/p>\r\n

\u00a0In the modern approach to naming compounds containing variable-charge metals, called the Stock system<\/span><\/strong><\/span>, a variable-charge metal ion\u2019s positive charge is indicated by a Roman numeral in parentheses after the element name, followed by the word ion<\/em>. Thus, Fe2+<\/sup> is called the iron(II) ion, while Fe3+<\/sup> is called the iron(III) ion. The names for variable-charge metals must always<\/em> be given a Roman numeral.<\/p>\r\n

An older system used the endings -ic for when the metal had the larger of its possible negative charges and -ous for when the metal had the smaller of its possible negative charges instead of the Roman numerals.\u00a0 We will not use this older system.<\/p>\r\nNaming the Anion<\/strong>\r\n

The name of a monatomic anion consists of the stem of the element name, the suffix -ide<\/em>, and then the word ion<\/em>. Thus, as we have already seen, Cl\u2212<\/sup> is \u201cchlor-\u201d + \u201c-ide ion,\u201d or the chloride ion. Similarly, O2\u2212<\/sup> is the oxide ion, Se2\u2212<\/sup> is the selenide ion, and so forth. Table 3.3 \"Some Monatomic Anions\"<\/a> lists the names of some common monatomic ions.<\/p>\r\n\r\n

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Table 3.3<\/span> Some Monatomic Anions<\/strong><\/h5>\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
Ion<\/th>\r\nName<\/th>\r\n<\/tr>\r\n<\/thead>\r\n
F\u2212<\/sup><\/td>\r\nfluoride ion<\/td>\r\n<\/tr>\r\n
Cl\u2212<\/sup><\/td>\r\nchloride ion<\/td>\r\n<\/tr>\r\n
Br\u2212<\/sup><\/td>\r\nbromide ion<\/td>\r\n<\/tr>\r\n
I\u2212<\/sup><\/td>\r\niodide ion<\/td>\r\n<\/tr>\r\n
O2\u2212<\/sup><\/td>\r\noxide ion<\/td>\r\n<\/tr>\r\n
S2\u2212<\/sup><\/td>\r\nsulfide ion<\/td>\r\n<\/tr>\r\n
P3\u2212<\/sup><\/td>\r\nphosphide ion<\/td>\r\n<\/tr>\r\n
N3\u2212<\/sup><\/td>\r\nnitride ion<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n

The polyatomic ions have their own characteristic names, as we saw in Table 3.1 \"Some Polyatomic Ions\"<\/a>.<\/p>\r\n\r\n

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Example 6<\/h3>\r\n

Name each ion.<\/p>\r\n\r\n

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  1. Ca2+<\/sup><\/li>\r\n \t
  2. S2\u2212<\/sup><\/li>\r\n \t
  3. SO3<\/sub>2\u2212<\/sup><\/li>\r\n \t
  4. NH4<\/sub>+<\/sup><\/li>\r\n \t
  5. Cu+<\/sup><\/li>\r\n<\/ol>\r\n

    Solution<\/p>\r\n[reveal-answer q=\"964807\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"964807\"]\r\n

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    1. the calcium ion<\/li>\r\n \t
    2. the sulfide ion (from Table 3.3 \"Some Monatomic Anions\")<\/li>\r\n \t
    3. the sulfite ion (from Table 3.1 \"Some Polyatomic Ions\")<\/li>\r\n \t
    4. the ammonium ion (from Table 3.1 \"Some Polyatomic Ions\")<\/li>\r\n \t
    5. the copper(I) ion : Copper can form cations with either a 1+ or 2+ charge, so we have to specify the charge by using a Roman numeral.)[\/hidden-answer]<\/li>\r\n<\/ol>\r\n<\/div>\r\n
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      SKill Building Exercise<\/h3>\r\nName each Ion\r\n
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      1. Fe2+<\/sup><\/li>\r\n \t
      2. Fe3+<\/sup><\/li>\r\n \t
      3. SO4<\/sub>2\u2212<\/sup><\/li>\r\n \t
      4. Ba2+<\/sup><\/li>\r\n \t
      5. HCO3<\/sub>-<\/sup><\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n
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        Example 7<\/h3>\r\n

        Write the formula for each ion.<\/p>\r\n\r\n

          \r\n \t
        1. the bromide ion<\/li>\r\n \t
        2. the phosphate ion<\/li>\r\n \t
        3. the copper 1+<\/sup> ion<\/li>\r\n \t
        4. the magnesium ion<\/li>\r\n<\/ol>\r\n

          Solution[reveal-answer q=\"634959\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"634959\"]<\/p>\r\n\r\n

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          1. Br\u2212<\/sup><\/li>\r\n \t
          2. PO4<\/sub>3\u2212<\/sup><\/li>\r\n \t
          3. Cu1+ <\/sup><\/li>\r\n \t
          4. Mg2+<\/sup>[\/hidden-answer]<\/li>\r\n<\/ol>\r\n<\/div>\r\n
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            SKILL-BUILDING EXERCISE<\/h3>\r\n

            Write the formula for each ion.<\/p>\r\n\r\n

              \r\n \t
            1. the fluoride ion<\/li>\r\n \t
            2. the carbonate ion<\/span><\/li>\r\n \t
            3. the tin4+<\/sup> ion<\/span><\/li>\r\n \t
            4. the potassium ion<\/span><\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n

              Naming Compounds<\/span><\/h3>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n
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              Now that we know how to name ions, we are ready to name ionic compounds. We do so by placing the name of the cation first, followed by the name of the anion, and dropping the word ion<\/em> from both parts.<\/p>\r\n

              For example, what is the name of the compound whose formula is Ba(NO3<\/sub>)2<\/sub>?<\/p>\r\n\r\n

              \"image\"<\/div>\r\n

              The compound\u2019s name does not indicate that there are two nitrate ions for every barium ion. You must determine the relative numbers of ions by balancing the positive and negative charges.<\/p>\r\n

              If you are given a formula for an ionic compound whose cation can have more than one possible charge, you must first determine the charge on the cation before identifying its correct name. For example, consider FeCl2<\/sub> and FeCl3<\/sub>. In the first compound, the iron ion has a 2+<\/sup> charge because there are two Cl\u2212<\/sup> ions in the formula (1\u2212<\/sup> charge on each chloride ion). In the second compound, the iron ion has a 3+<\/sup> charge, as indicated by the three Cl\u2212<\/sup> ions in the formula. These are two different compounds that need two different names. By the Stock system, the names are iron(II) chloride and iron(III) chloride.<\/p>\r\n\r\n

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              Example 8<\/h3>\r\n

              Name each ionic compound.\u00a0 Use Roman numerals only<\/em> when needed.<\/p>\r\n\r\n

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              1. Ca3<\/sub>(PO4<\/sub>)2<\/sub><\/li>\r\n \t
              2. (NH4<\/sub>)2<\/sub>Cr2<\/sub>O7<\/sub><\/li>\r\n \t
              3. KCl<\/li>\r\n \t
              4. CuCl<\/li>\r\n \t
              5. SnF2<\/sub><\/li>\r\n<\/ol>\r\n

                Solution<\/p>\r\n[reveal-answer q=\"167230\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"167230\"]\r\n

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                1. calcium phosphate<\/li>\r\n \t
                2. ammonium dichromate (the prefix di- is part of the name of the anion, as in Table 3.1 \"Some Polyatomic Ions\")<\/li>\r\n \t
                3. potassium chloride<\/li>\r\n \t
                4. copper(I) chloride<\/li>\r\n \t
                5. tin(II) fluoride [\/hidden-answer]<\/li>\r\n<\/ol>\r\n<\/div>\r\n
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                  Skill-building Exercise<\/h3>\r\n
                  \r\n\r\nName each ionic compound. Use Roman numerals\u00a0only<\/em> when neccessary.\r\n
                    \r\n \t
                  1. ZnBr2<\/sub><\/li>\r\n \t
                  2. Fe(NO<\/span>3<\/sub>)<\/span>3<\/sub><\/li>\r\n \t
                  3. Al<\/span>2<\/sub>O<\/span>3<\/sub><\/li>\r\n \t
                  4. AuF<\/span>3<\/sub><\/li>\r\n \t
                  5. AgF<\/span><\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n

                    Figure 3.7 \"A Guide to Naming Simple Ionic Compounds\"<\/a> is a synopsis of how to name simple ionic compounds.<\/p>\r\n\r\n

                    \r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"2076\"]\"image\" Figure 3.7 A Guide to Naming Simple Ionic Compounds.\u00a0<\/em>Follow these steps to name a simple ionic compound.[\/caption]\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n
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                    Concept Review Exercises<\/h3>\r\n
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                    1. Briefly describe the process for naming an ionic compound.<\/li>\r\n \t
                    2. In what order do the names of ions appear in the names of ionic compounds?<\/li>\r\n \t
                    3. When do you need a Roman numeral in the name of an ionic compound? Give an example.\u00a0 When are you not allowed to have a Roman numeral in an ion compound name?<\/li>\r\n<\/ol>\r\n<\/div>\r\n
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                      ANswers<\/h3>\r\n[reveal-answer q=\"432731\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"432731\"]\r\n
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                      1. Name the cation and then the anion.<\/li>\r\n \t
                      2. the cation name followed by the anion name<\/li>\r\n \t
                      3. An ionic compound in which the metal cation can have more than one possible charge must have a Roman numeral. For example FeCl3<\/sub> is iron(III) chloride but FeCl2<\/sub> is iron(II) chloride.\u00a0 Metals that always have the same charge as a cation\u00a0 are not given a Roman numeral,\u00a0 For example MgCl2<\/sub> is simply magnesium chloride because the magnesium ion is always Mg2<\/sup> .\u00a0[\/hidden-answer]\r\n
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                        <\/div>\r\n<\/div>\r\n<\/div>\r\n
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                        Key Takeaway<\/h3>\r\n