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Chapter 8. Chemical Nomenclature

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. Chemical Nomenclature. Why Bother? How do you speak Al 2 (SO 4 ) 3 ? What system do we use?

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Chapter 8. Chemical Nomenclature

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  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 Al2(SO4)3 ? What system do we use? IUPACInternational 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, MgBr2, Fe2O3 Ternary, contains three elements; two are in a polyatomic anion: NaNO3, NH4Cl, Cr2(SO4)3

  5. Naming Binary Ionic Compounds What is the charge on the metal ion? Fixed: Group 1A, +1; Group 2A, +2 Al3+, Ga3+, Zn2+, Cd2+, Ag1+ Examples: NaCl, Al2O3, 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, FeBr2, Fe2O3 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, Fe2O3 CuCl, CuCl2 SnF2, SnF4 Hg2Cl2, HgCl2

  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; Fe2O3 ferric oxide CuCl cuprous chloride CuCl2 cupric chloride SnF2 stannous fluoride SnF4 stannic fluoride Hg2Cl2 mercurous chloride HgCl2 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: CO32- carbonate ClO1- hypochlorite NO31- nitrate ClO31- chlorate PO43- phosphate C2H3O21- acetate SO42- sulfate CH3COO1- acetate OH1- hydroxide CN1- cyanide

  10. Naming Ternary Ionic Compounds There is one polyatomic cation NH41+, 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 CaCl2 Mercurous iodide Mg(NO3)2 Mercury(II) iodide Al2(SO4)3 Silver nitrate FeCl3 Ammonium bromide AgBr Tin(II) hydroxide MnO2 Sodium cyanide NH4NO3 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: 1 mono 4 tetra 2 di 5 penta 3 tri 6 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. CO Carbon monoxide CO2 Carbon dioxide N2O 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 N2O5 dinitrogen pentoxide Some compounds are known only by common names. H2O water NH3 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 NO2 Carbon tetrachloride SO3Phosphorus trichloride SiO2 Selenium dibromide TiO2 Dinitrogen tetroxide NO Sulfur dioxide P2O5 Xenon tetrafluoride Fe2O3 Diantimony Trioxide

  18. Naming Acids Types of acids: Binary, contains two elements: HCl, HBr, H2S Ternary, contains three elements; two are in a polyatomic ion: HNO3, H2SO4, H3PO4

  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 (aqueoussolution); they ionize. HCl + H2O  H3O1+ + Cl1- H3O1+ 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: H2SO4 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: H2CO3HClO HNO3 HClO3 H3PO4 HC2H3O2 H2SO4 CH3COOH HOH HCN (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 HNO3 Carbonic acid H2O Hydrogen iodide H2S Hypochlorous acid HF Hydrocyanic acid H3PO4 Acetic acid HI (aq) Chloric acid

  25. Naming Mixed Salts Mixed salts are compounds in which Na1+ or K1+ combine with H1+ and an anion with -2 or -3 charge. Symbol: KHSO4 Name: metal cation, hydrogen, anion Potassium hydrogen sulfate

  26. Naming Mixed Salts If the anion has -3 charge (PO43-), three cations are required to form a neutral compound. Symbol: NaH2PO4 Name: metal cation, prefix di-hydrogen, anion Sodium dihydrogen phosphate Symbol: K2HPO4 Name: prefix di-metal cation, hydrogen, anion Dipotassium hydrogen phosphate

  27. More Practice Give NameGive Formula AgNO3 Magnesium sulfate CaS Ferric chloride NH3 Nitric acid NaHS Lead(IV) sulfate ZrO2 Sodium hydrogen carbonate H2SO4 Mercuric bromide Al2O3 Phosphorus trifluoride

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