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compounds
Worksheet-Answer Key
Name Date Nomenclature is a system of naming. This worksheet presents a widely used system of nomenclature for ionic compounds. There are two types of metal cations with different naming conventions discussed separately.
- Part A: Fixed charge (single charge) cations
- Part B: Variable charge (multiple charge) cations
Cations with a single, fixed charge
Cations have a positive charge. They are formed from metals, which lie on the left side of the periodic table. The main group (Groups 1-8) metals form cations with a single, fixed charge. The charge is the same as the Group (column) number on the periodic table. The cation name is formed by adding the word “ion” after the element name. For example, the element sodium (Na) is found in Group 1. It ionizes to form the “sodium ion” represented as Na+. The charge is +1 because it is in Group 1. Never The big picture: How this worksheet is organized: Always Use a Roman numeral
Anions have a negative charge. They are formed from nonmetals, which lie on the right side of the periodic table. The negative charge is found using the Octet Rule as eight (8) minus the Group number. Anions always have a single, fixed charge. The anion name is formed by changing the element name suffix to “-ide” and adding the word “ion” after the element name. For example, the element chlorine (Cl) is found in Group 7. It ionizes to form the “chloride ion” represented as Cl-. The charge is - 1 because it is in Group 7, and 8 - 7 = 1. Ionic compounds are formed by cation-anion pairs in electrically neutral ratios. They are named using the cation name first, followed by the anion name, excluding the word “ion.” For example, sodium ion (Na+) and chloride ion (Cl-) form the compound sodium chloride. Its formula is NaCl, which is electrically neutral because sodium ion is + and chloride ion is - 1. As a second example, magnesium chloride has the formula MgCl 2. The subscript indicates 2 chloride ions (Cl-) per 1 magnesium ion (Mg2+). The subscript “1” is always implied and never written. Note: There is never any charge indicated in the name of a compound having a cation with a single, fixed charge. The single, fixed charge is obvious to a chemist.
compounds
Worksheet-Answer Key
Cations with a variable/multiple charges
Some transition metals have multiple possible cation charges. A roman numeral (I, II, III, IV, V, …) must be used in the cation and ionic compound naming system to distinguish between the charges. For example, iron (Fe) can form the iron (II) ion and also the iron (III) ion, denoted Fe2+^ and Fe3+, respectively. Iron (II) oxide and iron (III) oxide are distinct compounds, with electrically neutral formulas FeO and Fe 2 O 3 , respectively.
compounds
Worksheet-Answer Key
iron (II) oxide ___FeO____________ iron (III) oxide ___Fe 2 O 3 ___________ lead (II) chloride ___PbCl 2 ___________ lead (IV) iodide ___PbI 4 ____________ cobalt (II) chloride ___CoCl 2 ___________ cobalt (III) chloride ___CoCl 3 ___________ Exercise 3. Provide the formula for each compound.
Mixed cation types
The first step in naming an ionic compound is to determine whether or not the cation can exhibit multiple charges. This requires memorization. Learn the following procedure.
- The main group (Groups 1-8) elements always have a single charge, determined by the column on the periodic table.
- Silver and zinc are the only transition metals with a single charge. Memorize the ionic charges for Ag+^ and Zn2+.
- All other transition metals have multiple charges. Use a roman numeral to indicate the cation charge, which can be figured out from the given information. Exercise 4. Provide the name for each compound.
compounds
Worksheet-Answer Key
FeO __iron (II) oxide______ NaCl __sodium chloride____ CuBr 2 _copper (II) bromide ZnO __zinc oxide________ K 3 P __potassium phosphide CaS __calcium sulfide_____ Ag 2 S __silver sulfide_______ CoI 3 __cobalt (III) iodide____ Be 3 N 2 __beryllium nitride_____ NaCl ___sodium chloride_____
