Chapter 8. Chemical Nomenclature

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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 to devise these names.

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Chemical Nomenclature

• Why Bother?
• How do you speak Al2(SO4)3 ?
• What system do we use?
• IUPAC International Union of Pure and
  Applied Chemistry

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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.

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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

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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

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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

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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

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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

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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

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Naming Ternary Ionic Compounds

• There is one polyatomic cation
• NH41, ammonium
• Name it, then name anion properly

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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.

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Practice

• Give Name Give 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

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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

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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

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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

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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.

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Practice

• Give Name Give Formula
• NO2 Carbon tetrachloride
• SO3 Phosphorus trichloride
• SiO2 Selenium dibromide
• TiO2 Dinitrogen tetroxide
• NO Sulfur dioxide
• P2O5 Xenon tetrafluoride
• Fe2O3 Diantimony Trioxide

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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

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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

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Naming Binary Acids

• The compounds become acidic in water solution
  (aqueous solution) 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

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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

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Naming Ternary Acids

• Know names of these ternary acids. They are
  related to "must know" polyatomic anions
• H2CO3 HClO
• HNO3 HClO3
• H3PO4 HC2H3O2
• H2SO4 CH3COOH
• HOH HCN (aq)

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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.

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Practice

• Give Name Give Formula
• HBr (aq) Sulfuric acid
• HNO3 Carbonic acid
• H2O Hydrogen iodide
• H2S Hypochlorous acid
• HF Hydrocyanic acid
• H3PO4 Acetic acid
• HI (aq) Chloric acid

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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

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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

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More Practice

• Give Name Give Formula
• AgNO3 Magnesium sulfate
• CaS Ferric chloride
• NH3 Nitric acid
• NaHS Lead(IV) sulfate
• ZrO2 Sodium hydrogen carbonate
• H2SO4 Mercuric bromide
• Al2O3 Phosphorus trifluoride