629 CER Modular Laboratory Program in Chemistry

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1 M I S C 629 CER Modular Laboratory Program in Chemistry editor: M. L. Gillette Naming Inorganic Chemical Substances prepared by M. L. Gillette, Indiana University Kokomo, and H. A. Neidig, Lebanon Valley College Purpose of the Exercise Use a universal systematic method for naming inorganic chemical substances. Derive substance names from chemical formulas, and chemical formulas from substance names. Background Required You should be familiar with the names and chemical symbols of the elements, and the relative positions of metals and nonmetals in the periodic table. You should also know how to interpret a chemical formula. Background Information It is vital that people around the world use a common language when referring to any of the seemingly infinite number of chemical substances that exist. The universal nomenclature system currently in use is based on the identity and number of atoms making up one unit of the substance. To clarify what may initially seem like a confusing system, we will outline the process of naming an inorganic substance, using a flowchart. This will help us focus on the characteristics of the substance s formula, hence, those of its name. The flowchart we will use is shown in Figure 1 on the next page. Following the Flowchart I. Distinguishing between Elements and Compounds If the chemical formula for a substance includes only one kind of atom, we say that the substance is an element, or that it is in elemental form. Sometimes, the elemental form of a substance includes multiple identical atoms joined together, such as O 2 (elemental oxygen). If this is the case, the substance s chemical formula will reflect this fact. However, if the substance s formula includes two or more different elements, we say that the substance is a compound. Illustration: Na, Cl 2, and S 8 are elements; H 2 O and Na 2 CrO 4 are compounds. Copyright 2002 Wadsworth Group. Brooks/Cole is an imprint of the Wadsworth Group, a division of Thomson Learning, Inc. Thomson Learning TM is a trademark used herein under license. For more information about this or any other Brooks/Cole products, contact: BROOKS/COLE, 511 Forest Lodge Road, Pacific Grove, CA USA; (Thomson Learning Academic Resource Center). ALL RIGHTS RESERVED. No part of this work may be reproduced, transcribed, or used in any form or by any means graphic, electronic, or mechanical, including photocopying, recording, taping, Web distribution, or information storage and/or retrieval systems without the prior written permission of the publisher. For permission to use material from this work, contact us by fax: ; phone: Printed in United States of America.

2 element one kind of atom substance two kinds of atoms two or more kinds of atoms compound three kinds of atoms 2 MISC 629/Naming Inorganic Chemical Substances binary ternary metal and nonmetal nonmetals only metal and nonmetal nonmetals only ionic covalent ionic covalent metal ion with one likely charge metal ion with several likely charges binary acids nonacidic metal ion with one likely charge metal ion with several likely charges binary oxyacids nonacidic Figure 1 Flowchart outlining the procedure used for naming inorganic chemical substances

3 MISC 629/Naming Inorganic Chemical Substances 3 II. Naming Elements If the substance is in elemental form, we give it the name of the elemental symbol in the substance s formula, regardless of how many atoms are in the elemental unit. Illustration: Na is sodium, Cl 2 is chlorine, and S 8 is sulfur. III. Distinguishing between Binary and Ternary Compounds Most compounds fall into either of two categories, binary or ternary. The formulas of binary compounds include two different kinds of atoms. The formulas of ternary compounds include three different kinds of atoms. Illustration: NaCl is a binary compound; H 2 CO 3 is a ternary compound. IV. Distinguishing between Ionic and Covalent Compounds Most compounds whose formulas include both metallic and nonmetallic atoms are ionic. Most compounds whose formulas include only nonmetallic atoms are covalent. In the context of nomenclature and most chemical behavior, hydrogen is considered a nonmetal. Illustration: NaCl is an ionic compound; H 2 CO 3 is a covalent compound. Ionic compounds contain one or more cations (positively charged ions) and one or more anions (negatively charged ions). Ions formed from single atoms are called monoatomic ions. Ions formed from two or more atoms are called polyatomic ions. Illustration: Na + and Cl are monoatomic ions; CO 2 3 is a polyatomic ion. Ionic compounds are electrically neutral. In each unit of the compound, the total positive charge contributed by the cation(s) is balanced by the total negative charge contributed by the anion(s). The cations in ionic compounds are usually metal ions. Some metals form cations with only one likely charge, while others form cations with several likely charges, depending upon reaction conditions. Figure 2 shows some commonly occurring monoatomic ions, including metals and nonmetals H + Li + N 3 O 2 O F Na + Mg 2+ Al 3+ S 2 Cl K + Ca 2+ Ti 2+ Cr 2+ Ti 4+ Cr 3+ Mn 2+ Fe 2+ Fe 3+ Co2+ Cu + Co 3+ Cu 2+ Zn 2+ Br Rb + Sr 2+ Ag + Cd 2+ Sn 2+ Sn 4+ I Cs + Ba 2+ Figure 2 Commonly occurring monoatomic ions, as positioned in the periodic table

4 4 MISC 629/Naming Inorganic Chemical Substances V. Naming Binary Compounds In order to name a binary compound, we must first decide whether it is ionic or covalent. A. Naming Ionic Binary Compounds If the compound is ionic, we must determine whether the metal component is one that forms cations with one or several likely charges. To do so, we refer to Figure 2 on the previous page. Compounds containing a metal that forms cations with only one likely charge: Name the metal ion first, using its elemental name, then the nonmetal ion, changing the ending of its name to ide. Illustration: Na 2 S is sodium sulfide; CaO is calcium oxide. Compounds containing a metal that forms cations with several likely charges: Name the metal ion first, using its elemental name. Immediately following the metal name, write the cation s charge in parentheses, using capital Roman numerals. You can determine the cation s charge by looking at the possible anion charge(s) and figuring out which combination of cation/anion charges results in an electrically neutral compound. Then name the nonmetal ion, changing the ending of its name to ide. The use of Roman numerals to indicate metal ion charges is called the Stock system. There are older systems for indicating metal ion charges, but we will not discuss them here. Illustration: FeO is iron(ii) oxide; Fe 2 S 3 is iron(iii) sulfide. B. Naming Covalent Binary Compounds Covalent binary compounds: Several covalent binary compounds are known only by their common, or familiar, names. For example, NH 3 is ammonia, and H 2 O is water. For most other covalent binary compounds, begin by naming the first element in the formula. Then name the second element, changing the ending of its name to ide. Illustration: IBr is iodine bromide. In some instances, two or more covalent binary compounds contain the same two elements in different ratios; for example, CO and CO 2. When naming these types of compounds, we indicate the number of each component present in the formula, using the prefixes shown in Table 1. For simplicity s sake, we do not use the prefix mono with the first element in a compound name. Illustration: CO is carbon monoxide (not monocarbon monoxide); CO 2 is carbon dioxide; N 2 O is dinitrogen monoxide. Table 1 Prefixes used to indicate the number of atoms in the formula of a chemical compound number prefix number prefix 1 mono 4 tetra 2 di 5 penta 3 tri 6 hexa Some covalent binary compounds containing hydrogen are acidic, which means that they release hydrogen ions in aqueous solutions. When dissolved in water, these compounds are called binary acids. When they are not dissolved in water, these compounds are named using the method described above. Hence, HCl(g) is hydrogen chloride, and H 2 S(g) is hydrogen sulfide (not dihydrogen monosulfide because only one H S combination exists).

5 MISC 629/Naming Inorganic Chemical Substances 5 Binary acids: Covalent binary compounds that release hydrogen ions when dissolved in water are named as shown in Table 2. Table 2 Chemical formulas and names of some binary acids chemical formula HF (aq) HCl (aq) HBr (aq) HI (aq) H 2 S (aq) name hydrofluoric acid hydrochloric acid hydrobromic acid hydroiodic acid hydrosulfuric acid VI. Naming Ternary Compounds In order to name a ternary compound, we must first determine whether it is ionic or covalent. A. Naming Ionic Ternary Compounds Many ionic ternary compounds contain one or more polyatomic ions. Table 3 lists some common polyatomic ions. These ions can combine with metals that form ions with only one likely charge or several likely charges. Table 3 Names and chemical formulas for some common polyatomic ions name chemical formula name chemical formula acetate C 2 H 3 O 2 hydrogen sulfite (bisulfite) HSO 3 ammonium NH 4 + hydroxide OH carbonate CO 3 2 hypochlorite* ClO chlorate* ClO 3 nitrate NO 3 chlorite* ClO 2 nitrite NO 2 chromate CrO 4 2 oxalate C 2 O 4 2 cyanide CN perchlorate* ClO 4 dichromate Cr 2 O 7 2 permanganate MnO 4 dihydrogen phosphate H 2 PO 4 phosphate PO 4 3 hydrogen carbonate (bicarbonate) HCO 3 sulfate SO 4 2 hydrogen phosphate HPO 4 2 sulfite SO 3 2 hydrogen sulfate HSO 4 *Bromine (Br) and iodine (I) form analogous anions, which are named accordingly. Compounds containing a metal that forms cations with only one likely charge: Name the cation first, then the anion. If the anion is monoatomic, name it using its elemental name, changing the ending to ide. If the cation or anion is polyatomic, use the name from Table 3. Illustration: NH 4 Cl is ammonium chloride; NaClO 3 is sodium chlorate. Compounds containing a metal that forms cations with several likely charges: Name the metal first, using its elemental name. Then write the metal ion s charge in parentheses, using capital Roman numerals. Then name the anion. If the anion is polyatomic, use the name from Table 3. Illustration: CuCO 3 is copper(ii) carbonate; Fe(NO 3 ) 3 is iron(iii) nitrate. B. Naming Oxyacids, Covalent Ternary Compounds Containing Oxyanions All but two of the anions in Table 3 contain oxygen. We refer to these oxygen-containing anions as oxyanions. When hydrogen atom(s) replace the metal ion(s) in an ionic ternary compound containing an oxyanion, the result is a

6 6 MISC 629/Naming Inorganic Chemical Substances covalent ternary compound that we call an oxyacid. For example, H can replace Na in NaClO 3, resulting in HClO 3, an oxyacid. When dissolved in water, oxyacids release hydrogen ions to the solution. The best way to learn to distinguish oxyacids from other covalent ternary compounds is to become familiar with the oxyanions in Table 3. Oxyacids: Table 4 lists some of the oxyanions from Table 3, along with the oxyacids containing those anions. Table 4 Some oxyanions and their related oxyacids chemical formula chemical formula of oxyanion oxyanion name of related oxyacid oxyacid name ClO * hypochlorite HClO* hypochlorous acid ClO 2 * chlorite HClO 2 * chlorous acid ClO 3 * chlorate HClO 3 * chloric acid ClO 4 * perchlorate HClO 4 * perchloric acid NO 2 nitrite HNO 2 nitrous acid NO 3 nitrate HNO 3 nitric acid 2 SO 3 sulfite H 2 SO 3 sulfurous acid 2 SO 4 sulfate H 2 SO 4 sulfuric acid *Bromine and iodine form analogous oxyanions and oxyacids, which are named accordingly. Note that some of the oxyanions listed in Tables 3 and 4 contain the same nonmetal atom combined with different numbers of oxygen atoms. For example, nitrogen (N) is present in both NO 2 and NO 3 ; sulfur (S) in SO 2 3 and SO 2 4 ; and chlorine (Cl) in ClO, ClO 2, ClO 3, and ClO 4. We distinguish among such compounds using the following scheme. When the same nonmetal is present in two different oxyanions, we name the oxyanions and related oxyacids as follows. We give the oxyanion with fewer oxygen atoms the nonmetal name, changing the ending to ite, and we give the related acid the name of the oxyanion, changing the ending to ous. We give the oxyanion with more oxygen atoms the nonmetal name, changing the ending to ate, and we give the related oxyacid the name of the oxyanion, changing the ending to ic. Illustration: SO 2 3 is the sulfite ion, and H 2 SO 3 is sulfurous acid; SO 2 4 is the sulfate ion, and H 2 SO 4 is sulfuric acid. When the same nonmetal is present in four different oxyanions, as is the case for chlorine, bromine, and iodine, we distinguish among the oxyanions and related oxyacids as follows. We give the oxyanion with four oxygen atoms the nonmetal name, adding the prefix per and changing the ending to ate. We give the related oxyacid the oxyanion name, adding the prefix per and changing the ending to ic. We give the oxyanion with three oxygen atoms the nonmetal name, changing the ending to ate. We name the related oxyacid by changing the end of the oxyanion name to ic. We name the oxyanion with two oxygen atoms by changing the end of the nonmetal name to ite. We name the related oxyacid by changing the ending of the oxyanion name to ous. Finally, we give the oxyanion with one oxygen atom the nonmetal name, adding the prefix hypo and changing the ending to ite. We name the related oxyacid by adding the prefix hypo and changing the ending of the oxyanion name to ous. Illustration: ClO 4 is the perchlorate ion, and HClO 4 is perchloric acid; ClO 3 is the chlorate ion, and HClO 3 is chloric acid; ClO 2 is the chlorite ion, and HClO 2 is chlorous acid; ClO is the hypochlorite ion, and HClO is hypochlorous acid.

7 MISC 629/Naming Inorganic Chemical Substances 7 Example Problem Name the compound Al(ClO 4 ) 3. Solution Follow the flowchart in Figure 1 from substance to the correct general classification for Al(ClO 4 ) 3, and then name the compound. (a) Al(ClO 4 ) 3 is composed of more than one kind of atom, so it is a compound. (b) Al(ClO 4 ) 3 is composed of three kinds of atoms, so it is a ternary compound. (c) Al(ClO 4 ) 3 is composed of a metal (Al) and a polyatomic anion containing nonmetals (ClO 4 ), so it is an ionic ternary compound. (d) Aluminum ions occur only as Al 3+, so we give the cation its elemental name, aluminum. As listed in Table 4, ClO 4 is the perchlorate ion. Therefore, the name of Al(ClO 4 ) 3 is aluminum perchlorate. In This Exercise You will classify and name various substances, based on their chemical formulas. You will classify and write chemical formulas for other substances, based on their names. You will review a list of chemical formulas and related names, and correct the names so they are appropriate for the related formulas. Finally, you will review a list of compound names and related chemical formulas, and correct the formulas.

9 name partner section date Exercises 1. Classify the following substances, using the procedure outlined by the flowchart in Figure 1. For example: HCl is a covalent binary compound; NaI is an ionic binary compound with only one likely charge on the cation. (a) SO 2 (b) I 2 (c) H 2 SO 4 (d) K 2 SO 4 (e) CuCrO 4 (f) Co 2 (CrO 4 ) 3 2. Name the substances you classified in 1. (a) (b) (c) (d) (e) (f) MISC 629/Naming Inorganic Chemical Substances 9

10 10 MISC 629/Naming Inorganic Chemical Substances 3. Classify and name the following substances. chemical formula classification name (a) P 4 (b) LiBr (c) SnCl 2 (d) K 2 SO 3 (e) Fe(ClO 3 ) 2 (f) CS 2 (g) Sr(OH) 2 (h) N 2 O 4 (i) Al(NO 3 ) 3 (j) NO (k) NaIO 3 (l) HBrO 3 (m) KMnO 4 (n) Ti(CO 3 ) 2

11 name partner section date 4. Classify and write the chemical formulas for the following substances. name chemical formula classification (a) hypobromous acid (b) phosphorus pentachloride (c) sodium oxalate (d) calcium iodide (e) hydrobromic acid (f) dinitrogen pentaoxide (g) silver sulfide (h) iodous acid (i) iron(iii) phosphate (j) cobalt (k) titanium(ii) nitrate (l) calcium phosphate (m) manganese perchlorate (n) sodium sulfite (o) tetraphosphorus trisulfide MISC 629/Naming Inorganic Chemical Substances 11

12 12 MISC 629/Naming Inorganic Chemical Substances 5. The chemical name given to each of the compounds below is incorrect. Write the correct name for each compound, and briefly explain the basis of your correction. compound incorrect name correct name explanation (a) SnCl 4 tin chloride (b) SF 6 monosulfur hexafluoride (c) AlF 3 aluminum(iii) fluoride (d) HIO 4 iodic acid (e) F 2 difluorine 6. The formula given for each of the chemical names below is incorrect. Write the correct chemical formula for each compound, and briefly explain the basis of your correction. name incorrect chemical formula correct chemical formula explanation (a) copper(ii) carbonate Cu 2 CO 3 (b) potassium periodate KIO 3 (c) carbon tetrachloride CCl 3 (d) strontium sulfate SrSO 3 (e) barium nitrite BaNO 2 ISBN X

AP Chemistry (1 of 20) AP Chemistry (2 of 20) AP Chemistry (3 of 20) AP Chemistry (4 of 20) AP Chemistry (5 of 20) AP Chemistry (6 of 20)

AP Chemistry (1 of 20) AP Chemistry (2 of 20) AP Chemistry (3 of 20) AP Chemistry (4 of 20) AP Chemistry (5 of 20) AP Chemistry (6 of 20) Ions Ionic Charges of Representative Elements (1 of 20) (2 of 20) Formulas and Names of Common Metal Ions with More than One Common Ionic Charge Some Common Polyatomic Ions (3 of 20) (4 of 20) Naming Monatomic