Unit 5: Chemical Names & Formulas (Chapter 9) 1 2 Monatomic Ion Formation & Nomenclature Monatomic Ions consist of a ________________ atom with a positive or negative charge resulting from the gain or loss of one or more valence _____________________. Cation: any atom or group of atoms with a _________________ charge. Cations are formed by _____________ one or more electrons. _____________________ form cations! Group 1A and Group IIA form cations with positive charges equal to their ________ _________. Group IA metals are always _______ Group IIA metals are always _______ Anion: any atom or group of atoms with a _________________ charge. Anions are formed by _____________ one or more electrons. _____________________ form anions! The charge of any Group A nonmetal is determined by subtracting ____ from the ______ ______. Group VIA nonmetals are always _______ Group VIIA nonmetals are always ______. Using the periodic table below, label the elements whose ionic charges can be determined from their positions on the table. 3 Symbol Formula Change in Electrons Name of Ion of Ion Ca _____________ _________________________ ________________________________ F _____________ _________________________ ________________________________ Al _____________ _________________________ ________________________________ O _____________ _________________________ ________________________________ Na _____________ _________________________ ________________________________ P _____________ _________________________ ________________________________ Ar _____________ _________________________ ________________________________ C _____________ _________________________ ________________________________ H _____________ _________________________ ________________________________ _____________ _________________________ ________________________________ Many transition metals and representative elements can form more than one cation. Since the metal can form more than one ion, the name of the ion must include the charge in order to distinguish between the two. This charge is indicated by placing a Roman numeral after the name of the metal. EX: Lead can form both +2 and +4 ions. They are called _________________ and ____________________. It is important to note that when a metal forms only one possible ion, a Roman numeral is NOT needed and NEVER used in the name. We do not call Ca+2 the calcium II ion, because the +2 charge on the calcium ion is understood. The following metals NEVER have a Roman numeral in their name because they can form only one ion: Group 1A metals are always _______ Group 11A metals are always _______. Al is always _______ Zn & Cd are always _______ Ag is always __________ There is a pattern to help you remember these last three: 4 Symbol Formula of Ion Name of Ion Cr Cr+2 _____________________________ ________ _______________________ chromium III Ga _______________________ gallium I ________ Ga+3 _____________________________ Bi _______________________ bismuth III +5 ________ Bi _____________________________ The method used above to name the ions of metals that exhibit more than one charge was devised by the International Union of Pure and Applied Chemistry (IUPAC) and is called the Stock System. There is another method that can be used to name these ions. In classical nomenclature, when a metal forms more than one cation, the name of the metal (usually the Latin name) is modified with the suffixes -ous and -ic to distinguish between the two. The lower charge cation is given the -ous ending and the higher one, the -ic ending. EX: Pb+2 ~ the lower charge, is called plumbous. Pb+4 ~ the higher charge, is called plumbic. In addition to lead, you are responsible for naming the metals listed below in both systems: Stock Classical Cu+1 ______________________ cuprous Cu+2 ______________________ ______________________ Children Hg+1 ______________________ mercurous Hg+2 ______________________ ______________________ Have Fe+2 ______________________ ______________________ Fe+3 ______________________ ferric Fun Pb+2 ______________________ ______________________ +4 Pb ______________________ ______________________ Practicing Sn+2 ______________________ ______________________ Sn+4 ______________________ stannic Science 5 6 Naming Monatomic Ions 1. Metals that form only 1 common ion: element name + ion found in groups 1A (+1), 2A (+2), Al+3,Zn+2, Cd+2, Ag+1 always a positive charge EX: Na+ is called the sodium ion 2. Nonmetals (always only form 1 common negative ion): drop end of element’s name and add “ide” + ion found in groups 5A, 6A, 7A negative charge equals (8 - group #) EX: O-2 is called the oxide ion 3. Metals that form more than 1 common ion: Stock system - use Roman numerals or Classical method - change ending to “ous” or “ic” found in groups 3A (except aluminum), 4A, 5A, and the transition metals (except Ag+1,Zn+2 and Cd+2) always a positive charge EX: Stock System — Pb+2 lead (II) ion Pb+4 lead (IV) ion EX: Classical Method — Pb+2 plumbous ion Pb+4 plumbic ion always use one of these methods (stock or classical) when naming transition metals (except for the 3 listed above!) 7 1. What is the common charge of the following elements? (For metals with more than one common ionic charge, the number of electrons lost is indicated.) a. Zn _______ b. S _______ c. P _______ d. Br _______ e. Cd _______ f. Se _______ g. Pb (4 electrons lost) _______ h. Sn (2 electrons lost) _______ i. Cu (1 electron lost) _______ j. Fe (3 electrons lost) _______ 2. Name the ions in problem 1. (WRITE BOTH POSSIBLE NAMES FOR G-J.) a. __________________________ b. _______________________ c. _______________________ d. __________________________ e. _______________________ f. _______________________ g. __________________________ h. _______________________ i. _______________________ __________________________ _______________________ ______________________ j. __________________________ __________________________ 3. What are the possible charges on the following metals? Be sure to list all of them. a. copper _______________________ b. iron _______________________ c. tin _______________________ d. mercury _______________________ e. silver _______________________ f. lead _______________________ 4. Write the symbol and charge of each of the following ions. a. cuprous ion ____________________ b. iodide ion ____________________ c. plumbic ion ____________________ d. stannic ion ____________________ e. ferrous ion ____________________ f. sodium ion ____________________ g. chromium III ____________________ h. nitride ion ___________________ 8 : 1. Examine the data table. 2. Cut out the paper squares of each cation and anion separately. 3. Using the ion models, build the model of the formula. Remember, the total of positive charges must equal the total of negative charges. 4. Write the formula for the compound formed by writing the symbol and indicating the number of ions in your model (if more than one) as a subscript. EXAMPLE: If the model contains one Ca ion and two F ions the formula would be ________ 5. Write the name of the compound. These compounds are named by writing the name of the first ion, which is the name of the element, followed by the name of the second element with the ending, “-ide.” For the example in #4, the name would be ______________________. ELEMENTS FORMULA NAME sodium + chlorine aluminum + bromine calcium + iodine barium + nitrogen aluminum + fluorine silver + nitrogen aluminum + oxygen potassium + sulfur magnesium + sulfur aluminum + phosphorus 9 1. What is a binary compound? (consult your text) ______________________________________________________________________________ a. What are the components of a binary ionic compound? ___________________________________________________________________________ b. Which of the compounds in the data table are binary ionic compounds? ___________________________________________________________________________ 2. What is a cation? An anion? (define below) ______________________________________________________________________________ ______________________________________________________________________________ 3. Name ALL of the substances you made which combined in a one-to-one ratio. ______________________________________________________________________________ ______________________________________________________________________________ a. Why did they combine in a one-to-one ratio? ___________________________________________________________________________ 4. What does the total charge have to add up to in any correctly written formula for a compound? ___________________________________________ 10 +3 Na+1 +2 Na +1 Ba Al +2 K+1 Ba +3 +1 Al K Ba+2 +3 +2 Ca Mg+2 Al +2 +3 Ca Mg+2 Al Ag+1 +2 +1 Mg Ag +3 +1 Al Ag 11 12 -3 Br-1 -2 Br -1 O N -1 Br -2 O -3 -1 Cl -2 N Cl -1 O Cl -1 -3 -2 N I -1 S I -1 -2 -1 I S -3 -2 -1 P F S -1 F F-1 -3 P -3 P 13 14 Writing Formulas and Naming Binary Ionic Compounds 1. What are the components of a binary ionic compound? 2. What is the ending of the name of a binary ionic compound? 3. What condition must be met in writing a “balanced” formula for a compound? 4. Write formulas for compounds formed form the following pairs of ions. a. Sr+2, Se-2 _________________________ c. Ca+2, N-3 _________________________ b. K+1, O-2 _________________________ d. Co+3 , I-1 _________________________ 5. Write formulas for the following compounds. a. rubidium oxide ___________________ e. sodium nitrate ___________________ b. barium oxide ___________________ f. ferric chloride ___________________ c. potassium