Christopher G. Hamaker, Illinois State University, Normal IL © 2008, Prentice Hall Chapter 5 Language of Chemistry INTRODUCTORY CHEMISTRY INTRODUCTORY CHEMISTRY Fifth Edition by Charles H. Corwin

Chapter 5 2 The International Union of Pure and Applied Chemistry, IUPAC, has set rules for naming compounds. IUPAC set the rules for the naming and classification of inorganic compounds in These rules, referred to as IUPAC nomenclature are still in use today. IUPAC

Chapter 5 3 Most inorganic compounds do not contain the element carbon. –The exceptions are carbon dioxide, CO 2, and carbonates, which contain the ion CO 3 2–. There are 3 common classes of inorganic compounds: –Ionic (binary ionic, ternary ionic) –Molecular (covalent) –Acids (binary and ternary oxyacid) 5.1 Classification of Compounds

Chapter 5 4 Below is a flow chart for the classification of inorganic compounds. Classification of Compounds Metal + Nonmetal Nonmetal + Nonmetal HX

Chapter 5 5 Binary ionic compounds contain two elements: one metal and one nonmetal. –NaCl and AlCl 3 are binary ionic compounds. 5.2 Binary Ionic Compounds

Chapter 5 6 Recall, an ion is an atom or group of atoms with a charge. A positively charged ion is called a cation. A negatively charged ion is called an anion. Classification of Ions

Chapter 5 7 Below is a flow chart for the classification of ions. Classification of Ions + -

Chapter 5 8 Metal atoms can lose valence electrons and become positively charged cations. Cations are named for the parent atom followed by the word “ion” –Na + is named “sodium ion” –Al 3+ is named “aluminum ion” This rule applies for metal that usually form one ion. Cations

Chapter 5 9 Recall that Group 1 metals always form +1 ions and Group 2 ions always form +2 ions. Ag +, Zn 2+, and Cd 2+ & Al 3+ All the others are not predictable but you will have a hint in the name or chemical formula Predicting Cation Charges

Chapter 5 10 Group “B” metals (and most under the zig-zag line) If a metal can form more than one cation, it is named for the parent, followed by the charge in Roman numerals in parentheses, followed by the word “ion.” –Fe 2+ is the iron(II) ion –Fe 3+ is the iron(III) ion This is called the Stock system of naming cations. Metals That Form Multiple Ions

Chapter 5 11 Metals That Form Multiple Ions Old system uses Latin names (page 128) –Name of element ending in –ous or –ic –-ous (lower charge) –-ic (higher charge) See list on your yellow sheet…..”Transiton Metals” Example iron...“ferrum” -> ferrous (Fe +2 ) or ferric (Fe +3 ) tin.. “stannum” -> stannous (Sn +2 ) or stannic (Sn +4 ) lead. “plumbum”->plumbous(Pb +2 ) or plumbic (Pb +4 )

Chapter 5 12 Nonmetals gain electrons to form anions in a predictable fashion. Group VIIA/17 atoms gain 1 electron to form –1 ions: F –, Cl –, Br –, and I –. Group VIA/16 atoms gain 2 electrons to form –2 ions: O 2–, S 2–, Se 2–, and Te 2–. Group VA/15 atoms gain 3 electrons to form –3 ions: N 3–, P 3–, and As 3–. Predicting Anion Charges

Chapter 5 13 Nonmetals can gain valence electrons and become negatively charged anions. Monoatomic anions are named by dropping the end of the element name and adding the suffix –ide. –Br – is the bromide ion –O 2– is the oxide ion –N 3– is the nitride ion –S 2- is the sulfide ion Monoatomic Anions

Chapter 5 14 Shown are the elements on the periodic table and their common charges. Ion Charges Zn +2 Ag + Cd +2

Chapter 5 15 When naming ionic compounds, we combine the cation and anion name (drop the word “ion”) with the cation first and the anion second. MgO is composed of one magnesium ion and one oxide ion, therefore the name is magnesium oxide. What is the name of Fe 2 S 3 ? Fe 3+ is the iron(III) ion and S 2– is the sulfide ion, so the name is iron (III) sulfide. Naming Binary Ionic Compounds

Chapter 5 16 We can determine formula of a binary ionic compound from its name. What is the formula of iron (III) fluoride? Cobalt (III) has a +3 charge, Co 3+ ; and fluoride has a –1 charge, F –. Since the total charge must equal zero, the formula for cobalt (III) fluoride is CoF (3 X –1) = zero Formulas for Binary Ionic Compounds

Chapter 5 17 We can predict the formula of an ionic compound based on the formula of a similar compound. What is the formula of radium carbonate given that calcium carbonate is CaCO 3 ? Radium, Ra, and calcium are both in group 2 and will have the same ionic charge. The formula for radium carbonate is RaCO 3. Formulas for Binary Compounds

Chapter 5 18 If an ionic compound contains a metal which can have more than one ionic charge, we must determine the charge on the ion. The sum total charge of an ionic compound must equal zero. What is the charge on the chromium ion in Cr 3 N 2 ? –The charge on an nitride ion is always –3, so we have a total of 6 negative charges (2 × N 3– = 6 negative) –The sum of the charges on the chromium ions must be 6 positive –Cr x+ + Cr x+ + Cr x+ = 6 positive  Each Cr is 2+ Determining Ionic Charge

Chapter 5 19 An ionic compound is composed of positive and negative ions. A formula unit is the simplest representative particle of an ionic compound. A formula unit is neutral, so the total positive charge must equal the total negative charge in the formula unit. When writing chemical formulas, the cation (metal) goes first and the anion (nonmetal) goes second. Writing Ionic Formulas

Chapter 5 20 If the ions in the ionic compound have the same charge, the formula unit contains one of each ion. –Na + and Cl – combine to form NaCl. –Mg 2+ and S 2– combine to form MgS. If the charges are not equal, we must balance the positive and negative charges. –Ca 2+ and Cl – combine to form CaCl 2. –Na + and O 2– combine to form Na 2 O. Formulas of Ionic Compounds

Chapter 5 21 You can quickly verify that the chemical formula is written correctly by crossing over the number on each ion (not sign). The charge on the aluminum ion becomes the subscript for the oxygen, and the charge on the oxide ion becomes the subscript for the aluminum ion. Crossover Rule

Chapter 5 22 Sample Exercise Identifying Ionic and Molecular Compounds N 2 O- molecular (nonmetal/ nonmetal) Solution Which of these compounds would you expect to be ionic: N 2 O, Na 2 O, CaCl 2, SF 4 ? Na 2 O- ionic (metal/ nonmetal ) CaCl 2 - ionic (metal/ nonmetal) N 2 O- molecular (nonmetal/ nonmetal)

Chapter Ternary Ionic Compounds Ternary ionic compounds contain three elements, at least one metal and one nonmetal. A group of atoms bound together that has an overall charge is a polyatomic anion. –KNO 3 and Al(NO 3 ) 3 are ternary ionic compounds.

Chapter 5 24 Polyatomic anions generally contain one or more elements combined with oxygen. These anions are called oxyanions. Most oxyanions have names that end in the suffix -ate. –SO 4 2– is the sulfate ion –NO 3 – is the nitrate ion Polyatomic Anions

Chapter 5 25 Some oxyanions end in the suffix -ite. The oxyanions that end in -ate each have one more oxygen than the oxyanions than end in -ite. –NO 3- is nitrate, NO 2 – is the nitrite ion –SO 4 2- is sulfate, SO 3 2– is the sulfite ion Notice that the charge does not change as the number of oxygen atoms changes. Naming Oxyanions

Chapter 5 26 There are two common polyatomic ions that end in -ide: –hydroxide, OH – and cyanide, CN – There is one common polyatomic ion that has a + charge and acts like a metal –Ammonium NH 4 + More Polyatomic Anions

Chapter 5 27 Some Common Polyatomic Ions

Chapter 5 28 Follow the same rules as binary ionic compounds; if the charges are equal, the formula has one of each ion. –Mg 2+ and SO 4 2– combine to form MgSO 4 –K + and ClO 3 – combine to form KClO 3 If the charges are not equal, total charge must equal zero. If you have more than one polyatomic ion, it is placed in parentheses. –Al 3+ and (CO 3 ) 2– combine to form Al 2 (CO 3 ) 3. Formulas with Polyatomic Ions

Chapter 5 29 We name ternary ionic compounds like binary ionic compounds: the cation name followed by the anion name. K 2 CO 3 is named potassium carbonate. If we have a metal that can have than one oxidation state, we have to determine the charge on the metal. Co(ClO 3 ) 3 is composed of cobalt(III) and chlorate ions. cobalt(III) chlorate Naming Ternary Ionic Compounds

Chapter 5 30 Binary molecular compounds contain two elements and both are nonmetals. –Some examples of binary molecular compounds are ammonia (nitrogen trihydride, NH 3 ; methane, CH 4 ; carbon dioxide, CO 2 ; and tetraphosphorous trisulfide, P 4 S Molecular Compounds

Chapter 5 31 Binary molecular compounds are composed of two nonmetal elements. A molecule is the simplest representative particle of a binary molecular compound. Binary Molecular Compounds

Chapter 5 32 The first element in the compound is named first and the second element has the suffix -ide. The number of atoms of each element must be indicated by Greek prefixes. Naming Binary Molecular Compounds

Chapter 5 33 The molecular compound P 4 S 3 is used on match tips. What is the name of P 4 S 3 ? –There are 4 P atoms, use tetra- –There are 3 S atoms, use tri- –The name for P 4 S 3 is tetraphosphorous trisulfide. What is the name for N 2 O 4 ? –dinitrogen tetraoxide. Naming Binary Molecular Compounds

Chapter 5 34 There is one exception to the use of the Greek prefixes when naming binary molecular compounds. If there is only one atom of the first element, the mono- is not used. The prefix mono- is always used for the second element. –CO is carbon monoxide –XeF 6 is xenon hexafluoride An Exception

Chapter 5 35 Sample Exercise Relating the Names and Formulas of Binary Molecular Compounds (a) sulfur dioxide Solution Name the compounds (a) SO 2, (b) PCl 5, (c) Cl 2 O 3. Give the chemical formulas for (a) silicon tetrabromide, (b) disulfur dichloride. (b) phosphorus pentachloride (c) dichlorine trioxide (a) SiBr 4, (b) S 2 Cl 2

Chapter 5 36 An aqueous solution is produced when a compound dissolves in water. It is indicated by the symbol (aq). An acid is an aqueous solution containing hydrogen and one other nonmetal. HF is an acid. If ALL acids begin with “H”, then the anion must be used to name it 5.6 Naming Acids

Chapter Rules depending on anion –“_ide” –“_ate” –“_ite” If the anion in the acid ends in -ide, change the ending to -ic acid and add the prefix hydro-. –HCl (Chloride)  hydrochloric acid –HBr (bromide)  hydrobromic acid –HI (iodide)  hydroiodic acid Naming Acids

Chapter 5 38 If the anion in the acid ends in -ate, change the ending to -ic acid. –HNO 3 (nitrate)  nitric acid –HClO 3 (chlorate)  chloric acid –HClO 4 (perchlorate)  perchloric acid If the anion in the acid ends in -ite, change the ending to -ous acid. –HClO: hypochlorous acid –HClO 2 : chlorous acid Naming Acids

Chapter 5 39 Summary for Naming Acids

Chapter 5 40 Sample Exercise 2.14 Relating the Names and Formulas of Acids (a) anion CN – (cyanide) hydrocyanic acid. Solution Name the acids (a) HCN, (b) HNO 3, (c) H 2 SO 4, (d) H 2 SO 3. (b) NO 3 – (nitrate) nitric acid (c) SO 4 2– (sulfate) sulfuric acid. (d) SO 3 2– (sulfite) sulfurous acid