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Chapter 5 Nomenclature. Naming Starts with Classifying Compounds. Binary compounds: only 2 elements Compounds containing polyatomic ions Acids: formulas often start with H. Classifying Binary Compounds. Binary ionic compounds contain a metal and a nonmetal. Type I and II
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Naming Starts with Classifying Compounds • Binary compounds: only 2 elements • Compounds containing polyatomic ions • Acids: formulas often start with H
Classifying Binary Compounds • Binary ionic compounds contain a metal and a nonmetal. • Type I and II • Compounds containing two nonmetals • Type III • Compounds containing H and a nonmetal = Acids
Binary Ionic • Made of metal cation and nonmetal anion • Name by naming the ions
Metal Cations • Type I • Metals that can only have one possible charge • Charge determined by position on the Periodic Table • Type II • Metals that can have more than one possible charge • Metal cation’s charge determined from the charge on anion
Type I Binary Ionic Compounds • Contain Metal Cation from Groups 1A, 2A or Al, Ga, & In (metals with only one possible ionic charge) + Nonmetal Anion • Metal listed first in formula & name • Name metal cation first, name nonmetal anion second • Nonmetal anion named by changing the ending on the nonmetal name to –ide • Lets do some examples • Self-Check 5.1 Page 117
Type II Binary Ionic Compounds • Contain metal cation of possible variable ionic charge + nonmetal anion • Metal listed first in formula & name • Name metal cation first and nonmetal anion second
Type II Binary Ionic Compounds (cont.) • 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
Determining the Charge on a Cation – Au2S3 • Determine the charge on the anion • Au2S3: the anion is S, since it is in Group 6A, and 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 • Self-Check 5.2 Page 121
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.
Subscript Prefix 1 mono- (not used on first nonmetal) 2 di- 3 tri- 4 tetra- 5 penta- 6 hexa- 7 hepta- 8 octa- Prefixes • Drop last “a” in the prefix if the name begins with vowel
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.
Compounds Containing Polyatomic Ions (cont.) • 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.
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 ClO3- = chlorate BrO3- = bromate • If the polyatomic ion starts with H, add hydrogen- before the ions name and add 1 to the charge. CO32- = carbonate HCO3- = hydrogen carbonate
Patterns for Polyatomic Ions (cont.) • -ate ion • chlorate = ClO3- • -ate ion plus 1 O same charge, per- prefix • perchlorate = ClO4- • -ate ion minus 1 O same charge, -ite suffix • chlorite = ClO2- • -ate ion minus 2 O same charge, hypo-prefix, -ite suffix • hypochlorite = ClO-
Acids • Formulas always begin with H as first element • Can be thought of as consisting of H+ cation and anion • Binary acids have H+ cation and a nonmetal anion • Oxyacids have H+ cation and a polyatomic anion
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