3 CHEMISTRY 100 Dr. Jimmy Hwang Sections 5 and 7 Tu & Th 9:30a.m.-10:45a.m. Textbook: Zumdahl, Introductory Chemistry, 5 th Edition Office Hours: by appointment Ext (voic )
4 Overview In Chapter 5, our goals are for the students to: 1. Understand why it is important to have a system for naming compounds. 2. Learn how to name binary compounds of a metal and a nonmetal. 3. Learn how to name binary compounds containing only nonmetals. 4. Review the naming of Type I, Type II, and Type III binary compounds. 5. Learn the names of common polyatomic ions and how to use them in naming compounds. 6. Learn how the anion composition determines the acid’s name. 7. Learn names of common acids. 8. Learn to write the formula of a compound given its name.
5 Common Names - Exceptions H 2 O = water, steam, ice NH 3 = ammonia CH 4 = methane NaCl = table salt C 12 H 22 O 11 = table sugar
6 Naming Starts with Classifying Compounds Binary Compounds = only 2 elements Compounds containing polyatomic ions Acids = formula often starts with H
7 Classifying Binary Compounds Compounds containing a metal and a nonmetal are binary ionic –Type I and II Compounds containing two nonmetals –Type III Compounds containing H and a nonmetal = Acids
8 Binary Ionic Made of metal cation and nonmetal anion Name by naming the ions
9 Metal Cations Type I –Metals that can only have one possible charge –Determine charge by position on the Periodic Table Type II –Metals that can have more than one possible charge –Determine metal cation’s charge from the charge on anion
10 Type I Binary Ionic Compounds Contain Metal Cation + Nonmetal Anion Metal listed first in formula & name ¶Name metal cation first, name nonmetal anion second ¶Simple metal cation name is the metal name –simple metals are Groups 1A, 2A and Al, Ga & In ¶Nonmetal anion named by changing the ending on the nonmetal name to -ide
11 Naming Compounds 1. Cation first, then anion 2. Monatomic cation = name of the element Ca 2+ = calcium ion 3. Monatomic anion = root + -ide Cl = chloride CaCl 2 = calcium chloride Binary Ionic Compounds (Type I):
12 Memorize Table 5.1
13 Principle of Electrical Neutrality The principle that, in any ionic compound, the total positive charge must equal the total negative charge, i.e., a chemical compound must have a net charge of zero.
14 Determining the Charge on a Cation – Au 2 S 3 using the Principle of Electrical Neutrality ¬Determine the charge on the anion Au 2 S 3 - the anion is S, since it is in Group 6A, its charge is -2 Determine the total negative charge since there are 3 S in the formula, the total negative charge is -6 ®Determine the total positive charge since the total negative charge is -6, the total positive charge is +6 ¯Divide by the number of cations since there are 2 Au in the formula & the total positive charge is +6, each Au has a +3 charge
15 Type II Binary Ionic Compounds Contain Metal Cation + Nonmetal Anion Metal listed first in formula & name ¶Name metal cation first, name nonmetal anion second ¶Metal cation name is the metal name followed by a Roman Numeral in parentheses to indicate its charge –Determine charge from anion charge –Common Type II cations in Table 5.2 ¶Nonmetal anion named by changing the ending on the nonmetal name to -ide
16 Figure 2.22: The common cations and anions
17 Monatomic Ions 2.Transition metal cations (Figure 2.22) Memorize the charge of other metals in Figure 2.8. It is easy to remember the charges of the metal ions in the figures as follows: +1: all alkali metals, Ag +, Cu +, Hg : Al 3+, Co 3+, Cr 3+, Fe 3+, Mn 3+ (AC 2 FM) +4: Sn 4+, Pb 4+ +2: everything else Note that some metals have two charges (Type II).
18 FeCl 2 2 Cl - -2 so Fe is +2 iron(II) chloride FeCl 3 3 Cl - -3 so Fe is +3 iron(III) chloride Cr 2 S 3 3 S so Cr is +3 (6/2)chromium(III) sulfide Principle of Electrical Neutrality The principle that, in any ionic compound, the total positive charge must equal the total negative charge, i.e. a chemical compound must have a net charge of zero.
20 Naming Compounds (continued) metal forms more than one cation use Roman numeral in name PbCl 2 Pb 2+ is cation PbCl 2 = lead (II) chloride Binary Ionic Compounds (Type II):
24 Type III - Binary Compounds of 2 Nonmetals Name first element in formula first, use the full name of the element Name the second element in the formula as if it were an anion –However, remember these compounds do not contain ions! Use a prefix in front of each name to indicate the number of atoms Never use the prefix mono- on the first element
25 Prefixes Drop last “a” in the prefix if the name begins with vowel octa-8 hepta-7 hexa-6 penta-5 tetra-4 tri-3 di-2 mono- (not used on first nonmetal) 1 PrefixSubscript
26 NF 3 nitrogen trifluoride SO 2 sulfur dioxide N 2 Cl 4 dinitrogen tetrachloride NO 2 nitrogen dioxide N2ON2Odinitrogen monoxide Molecular Compounds 2.7 TOXIC ! Laughing Gas
27 Figure 5.1: A flow chart for naming binary compounds.
30 Compounds Containing Polyatomic Ions Polyatomic ions are charged entities that contain more than one atom –Must memorize name, formula and charge –Look for Patterns!! Polyatomic compounds contain one or more polyatomic ions Name polyatomic compounds by naming cation and anion –Non-polyatomic ions named like Type I and II Polyatomic Acids contain H + and a polyatomic anion
31 Patterns for Polyatomic Ions ¬Elements in the same column on the Periodic Table form similar polyatomic ions –same number of O’s and same charge ClO 3 - = chlorate BrO 3 - = bromate If the polyatomic ion starts with H, add hydrogen- before the ions name and add 1 to the charge CO 3 2- = carbonate HCO 3 - = hydrogen carbonate
32 Patterns for Polyatomic Ions -ate ion –chlorate = ClO 3 - -ate ion plus 1 O same charge, per- prefix –perchlorate = ClO 4 - -ate ion minus 1 O same charge, -ite suffix –chlorite = ClO 2 - -ate ion minus 2 O same charge, hypo- prefix, - ite suffix –hypochlorite = ClO -
34 Figure 5.2: Overall strategy for naming chemical compounds.
35 Acids Contain H + cation and anion Binary acids have H + cation and a nonmetal anion Oxyacids have H + cation and a polyatomic anion
38 Figure 5.3: A flow chart for naming acids. The acid is considered as one or more H + ions attached to an anion.
44 Writing the Formulas from the Names For Type III compounds, use the prefixes to determine the subscripts For Type I, Type II, polyatomic Compounds and Acids –Determine the ions present –Determine the charges on the cation and anion –Balance the charges to get the subscripts