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Chapter 8. Chemical Nomenclature Chemical nomenclature is the system of names used to distinguish chemical compounds from each other, and the rules needed.

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Presentation on theme: "Chapter 8. Chemical Nomenclature Chemical nomenclature is the system of names used to distinguish chemical compounds from each other, and the rules needed."— Presentation transcript:

1 Chapter 8. Chemical Nomenclature Chemical nomenclature is the system of names used to distinguish chemical compounds from each other, and the rules needed to devise these names.

2 Chemical Nomenclature Why Bother? How do you speak Al 2 (SO 4 ) 3 ? What system do we use? IUPAC International Union of Pure and Applied Chemistry

3 Chemical Nomenclature Three major categories of compounds: Ionic First element in formula is a metal. Molecular First element in formula is a nonmetal. Acid First element in formula is Hydrogen.

4 Naming Ionic Compounds Types of ionic compounds: Binary, contains two elements: NaCl, MgBr 2, Fe 2 O 3 Ternary, contains three elements; two are in a polyatomic anion: NaNO 3, NH 4 Cl, Cr 2 (SO 4 ) 3

5 Naming Binary Ionic Compounds What is the charge on the metal ion? Fixed: Group 1A, +1; Group 2A, +2 Al 3+, Ga 3+, Zn 2+, Cd 2+, Ag 1+ Examples:NaCl, Al 2 O 3, CdS Name cation as element, e.g. sodium Name anion with stem of element name, followed by suffix ide, e.g. chloride

6 Naming Binary Ionic Compounds What is the charge on the metal ion? Variable: All other metals Examples:CuO, FeBr 2, Fe 2 O 3 Name cation as element, followed by charge in Roman numerals, enclosed by parentheses, e.g. copper(II) Name anion with stem of element name, followed by suffix ide, e.g. oxide

7 Naming Binary Ionic Compounds What is the charge on the metal ion? The compound must be electrically neutral. Use the charge on the anion to figure out the charge on the metal. Examples:FeO, Fe 2 O 3 CuCl, CuCl 2 SnF 2, SnF 4 Hg 2 Cl 2, HgCl 2

8 Naming Binary Ionic Compounds An older naming system gives the suffix ic to the ion with the higher charge, and the suf- fix ous to the ion with the lower charge, following the (usually Latin) element stem. FeO ferrous oxide; Fe 2 O 3 ferric oxide CuCl cuprous chloride CuCl 2 cupric chloride SnF 2 stannous fluorideSnF 4 stannic fluoride Hg 2 Cl 2 mercurous chlorideHgCl 2 mercuric chloride

9 Naming Ternary Ionic Compounds Name metal as you would for a binary, with charge if necessary. Name anion as itself. Know these: CO 3 2- carbonate ClO 1- hypochlorite NO 3 1- nitrate ClO 3 1- chlorate PO phosphate C 2 H 3 O 2 1- acetate SO 4 2- sulfate CH 3 COO 1- acetate OH 1- hydroxide CN 1- cyanide

10 Naming Ternary Ionic Compounds There is one polyatomic cation NH 4 1+, ammonium Name it, then name anion properly

11 Formulas from Names Write symbol for metal ion first, then anion. Use the charges on the ions to determine how many of each ion are present in the formula. Charges must sum to zero. If a polyatomic ion appears more than once in a formula, enclose it in parentheses, followed by a subscript showing the number of times the ion occurs in the compound.

12 Practice Give NameGive Formula CaCl 2 Mercurous iodide Mg(NO 3 ) 2 Mercury(II) iodide Al 2 (SO 4 ) 3 Silver nitrate FeCl 3 Ammonium bromide AgBrTin(II) hydroxide MnO 2 Sodium cyanide NH 4 NO 3 Calcium phosphate

13 Naming Molecular Compounds These are all binary. Since the atoms do not have charges, use Greek numerical prefix- es to indicate the number of each atom in the molecule. Know these: 1mono4 tetra 2di5 penta 3tri6 hexa

14 Naming Molecular Compounds How to name them: 1.Prefix for first element in formula, omit if it's "mono" 2.Name first element 2.Prefix for second element in formula, 3.Give stem of second element followed by suffix ide. COCarbon monoxide CO 2 Carbon dioxide N 2 O Dinitrogen monoxide

15 Naming Molecular Compounds Details and exceptions: If last letter of prefix for number and first letter of element are both vowels, drop the last letter of the prefix: CO carbon monoxide N 2 O 5 dinitrogen pentoxide Some compounds are known only by common names. H 2 O waterNH 3 ammonia

16 Formulas from Names Write symbol for least electronegative element first, then most electronegative. Use prefixes to determine subscripts in formula. Metalloids are not metals, and their com- pounds are named as molecular com- pounds.

17 Practice Give NameGive Formula NO 2 Carbon tetrachloride SO 3 Phosphorus trichloride SiO 2 Selenium dibromide TiO 2 Dinitrogen tetroxide NOSulfur dioxide P 2 O 5 Xenon tetrafluoride Fe 2 O 3 Diantimony Trioxide

18 Naming Acids Types of acids: Binary, contains two elements: HCl, HBr, H 2 S Ternary, contains three elements; two are in a polyatomic ion: HNO 3, H 2 SO 4, H 3 PO 4

19 Naming Binary Acids Binary acids are gases as pure compounds. Symbol: HCl or HCl (g) Name: hydrogen + stem of nonmetal followed by suffix -ide. hydrogen chloride

20 Naming Binary Acids The compounds become acidic in water solution (aqueous solution); they ionize. HCl + H 2 O  H 3 O 1+ + Cl 1- H 3 O 1+ is what makes acids acidic. Symbol: HCl (aq) Name: prefix hydro- + stem of nonmetal followed by suffix -ic acid. hydrochloric acid

21 Naming Ternary Acids No distinction is made between pure ternary acids and those in aqueous (water) solution. Symbol: H 2 SO 4 Name: stem of central atom followed by suffix -ic acid. sulfuric acid

22 Naming Ternary Acids Know names of these ternary acids. They are related to "must know" polyatomic anions: H 2 CO 3 HClO HNO 3 HClO 3 H 3 PO 4 HC 2 H 3 O 2 H 2 SO 4 CH 3 COOH HOHHCN (aq)

23 Naming Acids and Anions Useful Generalization: If the name of an anion ends in -ide, its aqueous acid is named as hydrostemic acid. If the name of an anion ends in -ate, its acid is named as stemic acid.

24 Practice Give NameGive Formula HBr (aq)Sulfuric acid HNO 3 Carbonic acid H 2 OHydrogen iodide H 2 SHypochlorous acid HFHydrocyanic acid H 3 PO 4 Acetic acid H I (aq)Chloric acid

25 Naming Mixed Salts Mixed salts are compounds in which Na 1+ or K 1+ combine with H 1+ and an anion with -2 or -3 charge. Symbol: KHSO 4 Name: metal cation, hydrogen, anion Potassium hydrogen sulfate

26 Naming Mixed Salts If the anion has -3 charge (PO 4 3- ), three cations are required to form a neutral compound. Symbol: NaH 2 PO 4 Name: metal cation, prefix di-hydrogen, anion Sodium dihydrogen phosphate Symbol: K 2 HPO 4 Name: prefix di-metal cation, hydrogen, anion Dipotassium hydrogen phosphate

27 More Practice Give NameGive Formula AgNO 3 Magnesium sulfate CaSFerric chloride NH 3 Nitric acid NaHSLead(IV) sulfate ZrO 2 Sodium hydrogen carbonate H 2 SO 4 Mercuric bromide Al 2 O 3 Phosphorus trifluoride


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