Zumdahl Zumdahl DeCoste CHEMISTRY World of
Chapter 4 Nomenclature
Copyright © Houghton Mifflin Company4-3 Goals of Chapter 4 1.Name binary compounds of metal and non- metal 2.Name binary compounds containing only non-metals 3.Learn names of polyatomic ions and how to use them in naming 4.Learn common acids and how to name them 5.Write the formula of a compound when name is given
Copyright © Houghton Mifflin Company4-4 Binary compound: composed of two elements (bi-) Compounds that contain a metal and nonmetal Compounds that contain two nonmetals
Copyright © Houghton Mifflin Company4-5 * 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: NaCl (sodium chloride), not ClNa (Chloride sodium) Sum of all charges must equal zero
Copyright © Houghton Mifflin Company4-6 Table 4.1
Copyright © Houghton Mifflin Company4-7 Type I Binary Compounds: The metal present only forms one type of cation. contain a positive ion (cation) and a negative ion (anion) Group 1 and 2 metals (sometimes Group 3) See Table 4.1
Copyright © Houghton Mifflin Company4-8 Rules for naming 1. The cation is always named first and the anion named second 2. A simple cation (obtained from a single atom) takes its name from the name of the element 3. 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 Company4-9 Examples of Type I Binary Compounds NaCl Sodium Chloride Na +1 combines with Cl -1, sum is zero KI Potassium Iodide K +1 combines with I -1, sum is zero MgCl 2 Magnesium Chloride Mg +2 combines with 2 Cl -1, sum is zero
Copyright © Houghton Mifflin Company4-10 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
Copyright © Houghton Mifflin Company4-11 Rules for naming 1. Use basically same procedure as Type I, except 2. Use Roman Numerals to designate charge on cations (i.e. Fe2+ = Iron (II)) 3. 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 Fe2+ = ferrous ion and Fe3+ = ferric ion.
Copyright © Houghton Mifflin Company Do not use Roman numerals for Type I compounds!
Copyright © Houghton Mifflin Company4-13 Example of Type II Binary Compounds FeCl 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 Company4-14 Table 4.2
Copyright © Houghton Mifflin Company4-15 Type III Binary Compounds: compounds containing only nonmetals See prefixes in Table 4.3 Rules for naming 1. The first element in the formula is named first 2. The second element named as though it were an anion (oxygen → oxide) 3. Prefixes are used to denote the numbers of atoms present (O2 = dioxide)
Copyright © Houghton Mifflin Company The prefix mono- is never used when naming the first element. (CO is carbon monoxide not monocarbon monoxide) 5. To avoid awkward pronunciation, drop final o or a of prefix when second element is oxygen
Copyright © Houghton Mifflin Company4-17 Prefixes are: Mono = 1 Di = 2 Tri = 2 Tetra = 4 Penta= 5 Hexa= 6 Hepta = 7 Octa = 8
Copyright © Houghton Mifflin Company4-18 Some compounds are always referred to by the common names: H 2 O = water NH 3 = ammonia
Copyright © Houghton Mifflin Company4-19 Figure 4.1: A flow chart for naming binary compounds.
Copyright © Houghton Mifflin Company4-20 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)
Copyright © Houghton Mifflin Company4-21 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, chlorite, chlorate, perchlorate)
Copyright © Houghton Mifflin Company4-22 Rules for naming 1. Must recognize the polyatomic ion (break into two parts) 2. Use rules similar to naming binary ionic compounds 3. Treat polyatomic same as individual element, determine whether Type I, II, or III ****See flow chart on page 102
Copyright © Houghton Mifflin Company4-23 Table 4.4
Copyright © Houghton Mifflin Company4-24 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
Copyright © Houghton Mifflin Company4-25 Rules for naming 1. 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) 2. 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. 3. When the anion name ends in –ate, the suffix –ic is used (i.e. H2SO4 = sulfuric acid). 4. When anion name ends in -ite, the suffix –ous is used (i.e. H2SO3 = sulfurous acid) *See flow chart on page 105
Writing names from formulas Use naming process and work backwards
Copyright © Houghton Mifflin Company4-27 Figure 4.2: Overall strategy for naming chemical compounds.