CHEM 139: Zumdahl Chapter 5 page 1 of 9 CHAPTER 5: NOMENCLATURE Active Learning Problems: 7-9 End-of-Chapter Problems: 2-16, 17(e,f), 18(a,d-f), 19-21, 22(a,c,f), 23-50, 57, 59-60 A compound will display the same properties (e.g. melting and boiling point, solubility, etc.) because it consists of the same molecules or ions. Elements exist as individual atoms (atomic elements) or as molecules (molecular elements). Compounds are either molecules (molecular compounds of covalently bonded atoms) or ionic compounds (ions held together by ionic bonds). Types of Compounds binary compound: contains 2 elements ternary compound: contains 3 or more elements molecule: consist of nonmetal atoms held together by covalent bonds (e.g., H2O, CO2, etc.) ionic compound: a compound consisting of ions—usually metal cations with nonmetal or polyatomic anions—held together by ionic bonds (e.g., NaCl, Al2O3, CaBr2, KMnO4, BaSO4)CHEM 139: Zumdahl Chapter 5 page 2 of 9 Diatomic Molecules: Know these 7 elements exist as diatomic (two-atom) molecules: H2 N2 O2 F2 Cl2 Br2 I2 – Consider them the “diatomic seven” since there are seven of them, and six of them form a 7 on the Periodic Table. 5.2 NAMING A BINARY COMPOUNDS THAT CONTAIN A METAL AND A NONMETAL (TYPES I AND II) monoatomic ions: from a single atom (eg Na+, Cl–, O2–) polyatomic ions: consist of 2 or more atoms (eg. OH–, MnO4–, SO42–) cations: positively charged ions – Metal atoms and hydrogen lose electrons to form cations. Type I: Some metals always form the same charge: – Group IA elements form ions with a +1 charge: H+, Li+, Na+, K+ – Group IIA elements form ions with a +2 charge: Mg2+, Ca2+, Sr2+ , Ba2+ – aluminum ion = Al3+, silver ion = Ag+; zinc ion = Zn2+; cadmium ion = Cd2+ element name + ion → Na+=sodium ion or Ba2+=barium ion Type II. The Stock system is used to name most transition metals and other metals that form ions with different charges: – e.g., iron (Fe), a transition metal, forms 2 different ions: Fe2+ and Fe3+ – e.g., lead (Pb), in Group IVA, forms 2 different ions: Pb2+ and Pb4+ element name (charge in Roman numerals) + ion Sn2+=tin (II) ion and Sn4+=tin (IV) ionCHEM 139: Zumdahl Chapter 5 page 3 of 9 Example: Write the name for each of the cations below: Ag+ = __________________________ Li+ = __________________________ K+ = __________________________ Zn2+ = __________________________ Ni3+ = __________________________ H+ = __________________________ Hg2+ = ________________________ Pb4+ = ________________________ Cd2+ = ________________________ Al3+ = ________________________ Sr+2 = ________________________ Cr3+ = ________________________ ANIONS: negatively charged ions – Nonmetal atoms gain electrons to form anions – Group VIIA elements form –1 ions: F–, Cl–, Br–, I– – Group VIA elements form –2 ions: O2– , S2– – Group VA elements form –3 ions: N3–, P3– element stem name +”ide” + ion: O=oxygen → O2– = oxide ion F– = _____________________ S2– = _____________________ Br– = _____________________ N3– = _____________________ Cl– = _____________________ P3– = _____________________ Know the monatomic ions formed by the following Representative Elements and the four elements that form only one charge! Example: Give the formulas for each of the following ions: calcium ion = __________ sulfide ion = __________ silver ion = __________ nitride ion = __________ potassium ion = __________ aluminum ion = __________ phosphide ion = ________ fluoride ion = ________ zinc ion = __________CHEM 139: Zumdahl Chapter 5 page 4 of 9 POLYATOMIC IONS – Know the formulas and names of the following polyatomic ions: NH4+ = ammonium ion CrO42– = chromate ion CO32– = carbonate ion Hg22+ = mercury (I) ion Cr2O72– = dichromate ion HCO3– = bicarbonate or SO42– = sulfate ion hydrogen carbonate ion MnO4– = permanganate ion SO32– = sulfite ion ClO– = hypochlorite ion C2H3O2– = acetate ion NO3– = nitrate ion ClO2– = chlorite ion PO43– = phosphate ion NO2– = nitrite ion ClO3– = chlorate ion CN– = cyanide ion OH– = hydroxide ion ClO4– = perchlorate ion SCN– = thiocyanate ion O22– = peroxide ion FORMULAS OF IONIC COMPOUNDS – indicate the number of cations and anions present using symbols and subscripts Compounds must be neutral → positive (+ve) charges = negative (-ve) charges How to write chemical formulas of ionic compounds: 1. If both ions have charges that are exactly opposite (+1 & -1, +2 & -2, etc.), → the compound’s formula contains one of each ion – This also applies for polyatomic ions. Na+ + Cl– → NaCl and Na+ + CN– → NaCN K+ + Cl– → ___________ Mg2+ + O2– → ___________ Al3+ + N3– → ___________ K+ + NO3– → ______________ Mg2+ + SO42– → ______________ Al3+ + PO43– → ______________ 2. For monatomic ions with different charges, use the crossover method: → Make the number on the negative charge the subscript of the cation and the number on the positive charge the subscript of the anion. – Do NOT bring down the signs (+ or –), just the numbers! Ba2+ + Cl– Al3+ + O2– K+ + P3–CHEM 139: Zumdahl Chapter 5 page 5 of 9 3. For polyatomic ions, where ions have different charges, also use the crossover method: – Express more than one polyatomic ion with parentheses and subscripts. Sr2+ + NO3– Fe3+ + CO32– Zn2+ + PO43– EXCEPTION FOR CROSSOVER METHOD: Ions with 4+ and 2– charges! Pb4+ + O2– Ionic compound formulas have the lowest ratio of elements → NOT Pb2O4 but PbO2! Also applies to polyatomic ions! Sn4+ + SO42– NAMING IONIC COMPOUNDS Given known charges for some elements → get charge on transition metals! I. If one of each (cation & anion) present → opposite but equal charges! Example: For each of the following compounds: 1. Indicate the charge on the anion, then determine the charge on the cation given that the compound must be neutral. 2. Name each ion then name the compound. CuCl Name of CuCl: