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Unit 05

Unit 05. Chemical Nomenclature. Key Vocabulary. IUPAC - I nternational U nion of P ure and A pplied C hemistry Responsible for chemical naming worldwide Rules for naming and writing compounds

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Unit 05

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  1. Unit 05 Chemical Nomenclature

  2. Key Vocabulary • IUPAC - International Union of Pure and Applied Chemistry • Responsible for chemical naming worldwide • Rules for naming and writing compounds • Law of Definite Proportions – states that in samples of any chemical compound, the masses of the elements are always in the same proportions. • Chemical Formula - Symbols for its constituent elements are used; also shows number of atoms present in smallest representative unit of the substance.

  3. Key Vocabulary Oxidation Number – A measure of the charge of an atom if the electrons shared in bonding were held only by the more electronegative atom. For example, in water (H2O), oxygen is more electronegative than hydrogen. This would give oxygen all the electrons and an oxidation number of -2 and each hydrogen an oxidation number of +1. For simple atoms or ions, the oxidation number is equal to the ionic charge. For a neutral element like Helium (He), the oxidation number is 0.

  4. Key Vocabulary • Acid – compound that produces hydrogen ions (H+) in solution. • Base – compound that produces hydroxide ions (OH-) in solution. • Monatomic ion – a single atom with a + or – charge as a result of losing or gaining valence electrons. • Examples: Na + Al 3+ P 3- Br 1- • Polyatomic ion – a tightly bound group of atoms that behaves as a unit and carries a charge. • Examples: NH4+ NO3- OH - SO42-

  5. Transition Metals • Many of the cations of transition metals have more than one common ionic charge. • Examples - cations of Iron: Fe 2+ and Fe 3+ • This is also true for tin (Sn) and lead(Pb), the two metals in group 4A. • Use the stock system to name these • Stock system – as part of the name of the element, a Roman numeral in parentheses indicates the value of the charge. • Example: Fe 2+ = Iron (II) and Fe 3+ = Iron (III) • See page 144 in textbook, table 6.3 for more examples

  6. Naming Simple Ionic Compounds Ionic Compound = cation + anion • 1. write the name of the cation(metal) • If transition metal, useRoman numeral in parentheses • Example: Iron(II) • 2. write the anion(nonmetal)—change ending to –ide Ex. NaClcation = Sodium anion = Chlorine • Name = Sodium chloride

  7. Practice CaI2 Calcium iodide LiF Lithium fluoride MgO Magnesium oxide BeF2 Beryllium fluoride FeCl2 Iron (II) chloride

  8. Naming Ionic Compounds with Polyatomics • Polyatomic ion review • 1. write the name of the cation(metal) • If transition metal, may need Roman numeral in parentheses • 2. write the polyatomic ion— see common ones on your STAAR reference materials. • Special note: NH4+ is the only positive polyatomic ion • See pp. 146-147 in textbook, table 6.4

  9. Practice Na2SO4 Sodium sulfate CaCO3 Calcium carbonate Li3PO3 Lithium phosphite NH4Cl Ammonium chloride

  10. Writing Ionic Formulas • Criss Cross Method • 1. write chemical symbol for each element or polyatomic • 2. find the charge for each element or polyatomic • (Transition metal—look at the roman numeral) • 3. criss cross the charges to the opposite subscript • Notes: • if charges can be reduced, do so before crossing down • Use parentheses for polyatomics

  11. Practice Lithium fluoride LiF Calcium sulfide CaS Iron (III) chloride FeCl3 Potassium nitride K3N

  12. Practice with polyatomics Ammonium chloride NH4Cl Sodium sulfate Na2SO4 Magnesium carbonate MgCO3

  13. Naming Covalent Compounds • Covalent compound review • No charges • Share electrons • 2 or more nonmetals • Examples: CO2, H2O, SF2

  14. You will be receiving a copy of this soon! Use prefixes to designate the subscript

  15. CO2 • Carbon dioxide • Notes: • the second element still takes the –ide ending • Do not use mono for the first element

  16. Practice S2O4 Disulfurtetroxide FCl3 Fluorine trichloride N2O Dinitrogen monoxide NO2 Nitrogen dioxide

  17. Writing covalent formulas • Write the element symbol and add the prefix as subscript • DO NOT CRISS CROSS …PREFIX STAYS WITH ORIGINAL ELEMENT • Sulfur trioxide • Dinitrogentetrafluoride • Hexasulfurpentaiodide

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