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Chapter 2

Chapter 2. Names, Formulas and Properties. IUPAC: International Union of Pure and Applied Chemistry. Develop and maintain an international naming system for all pure substances. Every pure substance has an “IUPAC” name; we call this the systematic name.

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Chapter 2

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  1. Chapter 2 Names, Formulas and Properties

  2. IUPAC: International Union of Pure and Applied Chemistry Develop and maintain an international naming system for all pure substances. Every pure substance has an “IUPAC” name; we call this the systematic name.

  3. Why is a common naming system important? Because the system is recognized internationally, scientists from all over the world refer to a chemical substance by its systematic name. Communication is easier, there is less room for error.

  4. Systematic Name from IUPAC • Describes the compounds composition. • Enables you to write its chemical formula. • Enables you to predict some of its chemical properties. • (ie. potassium nitrate)

  5. potassium nitrate • Composed of potassium and nitrate ions. • Ionic compound (metal + non-metal). • Chemical formula: KNO3 • Like all potassium salts, potassium nitrate will dissolve readily in water.

  6. Binary Compounds Contain exactly two kinds of elements. Unionized table salt is an example of a binary compound. Which two elements does it contain? What is the chemical formula for table salt?

  7. Binary Molecular Compounds Contain NO metallic element. Eg. NH3, CO2, HF But NOT FeCl2 , Al2O3 or CH3OH

  8. Binary Molecular Names • First element named as usual. • Second element ending changed to “ide”. • Latin prefixes (mono, di, tri, tetra, penta, etc. see Table 2.1) tell how many atoms. • Mono prefix only used for second element.

  9. Examples • N2O4 is dinitrogen tetraoxide • SO3 is sulfur trioxide • CCl4 is carbon tetrachloride • CO is carbon monoxide

  10. Binary Molecular Formulas Write the chemical formula for these: • Dinitrogen trioxide • Sulfur pentafluoride • Oxygen dichloride

  11. Try These • SO2 • NCl3 • S2O3 • CO2

  12. Common Molecular Compounds • Some molecules have become known by common names- you need to memorize these compounds and their states: • Ozone- O3(g) • Ammonia-NH3(g) • Glucose-C6H12O6(s) • Ethanol-C2H5OH(l) • Sucrose-C12H22O11(s) • Hydrogen peroxide-H2O2(l) • Hydrogen sulfide-H2S(g) • Water-H2O(l) • Methane-CH4(g)

  13. Binary Ionic Compounds Eg. ZnCl2, AgBr, Al2S3 But NOT: PCl3, NO, C2H4Br KCl

  14. Binary Ionic Names • First element in the name and the formula is the metal; named as usual. • Second element, the non-metal, is named as an ion; ending is changed to “ide”. *** no prefixes are used. • The chemical formula shows the simplest whole number ratio of each type of ion in the compound.

  15. Examples • ZnO is zinc oxide • CaCl2 is calcium chloride • Al2S3 is aluminum sulfide

  16. Try These • MgO • AlCl3 • Na2S

  17. Binary Ionic Formulas • Overall ion charge must total zero. • Eg. Sodium chloride, Na+ and Cl-, so NaCl • Eg. Silver oxide, Ag+ and O2-, so Ag2O • Eg. Aluminum sulfide, Al3+ and S2-, so Al2S3 (Al3+Al3+S2-S2-S2- = 0)

  18. Try These • Zinc bromide • Sodium iodide • Calcium oxide • Magnesium nitride

  19. Give the Name or Formula • BaCl2 • PI3 • Scandium oxide • Li2S • Carbon tetrafluoride • SCl2

  20. Practice Problems: Read through “Model Problem 1” Page 44 #1-4 Page 45 #5-8

  21. Multivalent Ions • Some atoms are capable of forming more than one ion; most transition metals (groups 3-12) are able to form more than one cation. • Examples: lead, gold, mercury, nickel… • The top ion charge in the PTOE represents the most common ion.

  22. If you are given the formula of an ionic compound, you can determine the charge on the cation. Which lead cation, Pb2+ or Pb4+, is in PbCl2?

  23. Which lead cation, Pb2+ or Pb4+, is in PbCl2? • Step1: Begin by writing the two ions involved. You know that a chloride anion has a charge of 1-. You are not sure of the charge on the lead ion – it could be either 2+ or 4+, according to the PTOE.

  24. Which lead cation, Pb2+ or Pb4+, is in PbCl2? • Step 2: The compound must be electrically neutral.There are two chloride ions in PbCl2. Therefore, the single lead ion must have a charge of 2+ to balance the two chloride ions. The lead cation is Pb2+.

  25. Which lead cation, Pb2+ or Pb4+, is in PbCl2? • Step 3: Check your answer by adding the total charges in the compound: the total charges will add up to zero if the ion charges are correct. [+2 + (2*(-1)]=0

  26. Determine which iron cation, Fe2+ or Fe3+, is in each of the following binary ionic compounds: • a) FeCl2 • b) FeO • c) Fe2O3 • d) FeBr3

  27. Determine the charge of the cation in each of the following binary ionic compounds: • a) SnBr4 • b) FeN • c) PbO • d) PbO2

  28. Naming binary ionic compounds with multivalent ions: (Using the Stock System) • 1. First element in the name and the formula is the metal; named as usual. • 2. The charge on the cation (the metal ion) is written in brackets as a Roman numeral after the name of the metal; ie. lead (II) chloride. The “II” tells us that this compound is formed between Pb2+ and Cl-. • 3. Second element, the non-metal, is named as an ion; ending changed to “ide”. • 4. The chemical formula shows the simplest whole number ratio of each type of ion in the compound.

  29. Roman Numerals 1 – I 2 – II 3 – III 4 – IV 5 - V

  30. Write the chemical formula for copper (II) oxide. • Step1:The Roman numeral behind the metal represents the charge on the metal ion. Because the copper cation is named copper (II), it must be Cu2+. • Step2: Use the PTOE to determine the charge on the anion (the non-metal). According to the PTOE, the oxide anion is O2-.

  31. Write the chemical formula for copper (II) oxide. • Step3: The compound must be electrically neutral.Therefore, one formula unit must contain one copper (II) cation and one oxide anion; CuO. • Step 4: Check your answer by adding the total charges on the ions: +2 + (-2) = 0 The total charge adds up to zero. The formula is correct.

  32. Write the formula for each of the following ionic compounds: • a) colbalt (II) chloride • b) chromium (III) oxide • c) molybdenum (VI) chloride • d) lead (IV) oxide

  33. Determine which cation is in each of the following compounds. Then, write the name of the compound using the Stock system (system using Roman numerals). • a) SnO2 • b) CuBr • c) TiCl4 • d) PdO

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