Zumdahl De Coste World of CHEMISTRY Chapter 4

Zumdahl • De. Coste World of CHEMISTRY

Chapter 4 Nomenclature

Goals of Chapter 4 1. 2. 3. 4. 5. Name binary compounds of metal and nonmetal Name binary compounds containing only non-metals Learn names of polyatomic ions and how to use them in naming Learn common acids and how to name them Write the formula of a compound when name is given Copyright © Houghton Mifflin Company 3

Binary compound: composed of two elements (bi-) • • • Compounds that contain a metal and nonmetal Compounds that contain two nonmetals Binary ionic compound: contain a positive ion (cation) and a negative ion (anion) • To name these compounds, you simply name the ions • Positive ion always named first, negative ion named last • Example: Na. Cl (sodium chloride), not Cl. Na (Chloride sodium) • Sum of all charges must equal zero Copyright © Houghton Mifflin Company 4

Table 4. 1 Copyright © Houghton Mifflin Company 5

Type I Binary Compounds: The metal present only forms one type of cation. Group 1 and 2 metals (sometimes Group 3) • See Table 4. 1 • Rules for naming • • The cation is always named first and the anion named second • A simple cation (obtained from a single atom) takes its name from the name of the element • A simple anion (obtained from a single atom) is named by taking the first part of the element name (the root) and adding –ide. Copyright © Houghton Mifflin Company 6

Examples of Type I Binary Compounds • Na. Cl • Sodium Chloride • Na+1 combines with Cl-1, sum is zero • KI • Potassium Iodide • K+1 combines with I-1, sum is zero • Mg. Cl 2 • Magnesium Chloride • Mg+2 combines with 2 Cl-1, sum is zero Copyright © Houghton Mifflin Company 7

Type II Binary Compounds: The metal present can form two (or more) cations that have different charges. Many transition metals (some Group 3) • See Table 4. 2 • Rules for naming • • Use basically same procedure as Type I, except • Use Roman Numerals to designate charge on cations (i. e. Fe 2+ = Iron (II)) • Old system (sometimes still used): Ion with the higher charge has a name ending in –ic and ion with the lower charge has a name ending in –ous. For example Fe 2+ = ferrous ion and Fe 3+ = ferric ion. • Do not use Roman numerals for Type I compounds! Copyright © Houghton Mifflin Company 8

Example of Type II Binary Compounds • Fe. Cl 2 • Chloride is Cl-1, since there are 2 Chloride • • ions, the total charge is -2 Iron is transition metal with unknown charge Sum must be zero, so Fe must be +2 Proper way to write name is Iron (II) chloride Page 91 has more examples Copyright © Houghton Mifflin Company 9

Table 4. 2 Copyright © Houghton Mifflin Company 10

Type III Binary Compounds: compounds containing only nonmetals See prefixes in Table 4. 3 • Rules for naming • • The first element in the formula is named first • The second element named as though it were an anion (oxygen → oxide) • Prefixes are used to denote the numbers of atoms present (O 2 = dioxide) • The prefix mono- is never used when naming the first element. (CO is carbon monoxide not monocarbon monoxide) • To avoid awkward pronunciation, drop final o or a of prefix when second element is oxygen Copyright © Houghton Mifflin Company 11

Some compounds are always referred to by the common names: • H 2 O = water • NH 3 = ammonia Copyright © Houghton Mifflin Company 12

Figure 4. 1: A flow chart for naming binary compounds. Copyright © Houghton Mifflin Company 13

Polyatomic Ions: charged entities composed of several atoms bound together • • Entire group has a positive or negative charge Oxyanions: contain atom of a given element and different numbers of oxygen atoms (i. e. nitrate, nitrite) • Name of one with smaller number of oxygen atoms ends in –ite (nitrite, sulfite) • Name of one with larger number of oxygen atoms ends in –ate (nitrate, sulfate) • When more than two oxyanions in series, use hypo- (less than – for fewest) and per- (more than – for most) (hypochlorite, chlorate, perchlorate) • Rules for naming • Must recognize the polyatomic ion (break into two parts) • Use rules similar to naming binary ionic compounds • Treat polyatomic same as individual element, determine whether Type I, II, or III • See flow chart on page 102 Copyright © Houghton Mifflin Company 14

Table 4. 4 Copyright © Houghton Mifflin Company 15

Acids: molecules that produce H+ ions when dissolved in water • • First recognized by sour taste Molecule with one or more H+ ions attached to an anion Naming depends on whether or not oxygen present in anion Rules for naming • If anion does not contain oxygen: acid named with the prefix hydro- and the suffix –ic attached to the root of the name of the element (i. e. hydrochloric acid = HCl, hydrocyanic acid = HCN) • When anion contains oxygen: the acid name is formed from the root name of the central element of the anion or the anion name with a suffix of –ic or –ous. When the anion name ends in –ate, the suffix –ic is used (i. e. H 2 SO 4 = sulfuric acid). When anion name ends in -ite, the suffix – ous is used (i. e. H 2 SO 3 = sulfurous acid) • See flow chart on page 105 Copyright © Houghton Mifflin Company 16

Writing names from formulas Use naming process and work backwards

Figure 4. 2: Overall strategy for naming chemical compounds. Copyright © Houghton Mifflin Company 18