1. Chapter 6 Ionic and Molecular Compounds
6.3 Naming Ionic Compounds
Learning Goal Given the formula of an ionic compound, write the correct name; given the name of an ionic compound, write the correct formula.

2. Naming Ionic Compounds
The name of an ionic compound has two components:
the name of the metal ion which is written first and is the same as its elemental name
the name of the nonmetal ion which is written last by using the first syllable of its element name followed by ide
A space separates the name of the metal and nonmetal.

3. Names of Some Ionic Compounds

4. Guide to Naming Ionic Compounds with Metals That Form a Single Ion

5. Naming Ionic Compounds, Metal Forms a Single Ion
Write the name of an ionic compound with the formula Mg3N2. Step 1 Identify the cation and anion. The cation from Group 2A (2) is Mg2+, and the anion from Group 5A (15) is N3−. Step 2 Name the cation by its element name. The cation Mg2+ is magnesium.

6. Naming Ionic Compounds, Metal Forms a Single Ion
Write the name of an ionic compound with the formula Mg3N2. Step 3 Name the anion by using the first syllable of its element name followed by ide. The anion N3− is nitride. Step 4 Write the name for the cation first and the name for the anion second. Mg3N2 is magnesium nitride.

7. Learning Check
Select the correct name for each of the following ionic compounds.
CaS (1) calcium sulfur
(2) calcide sulfur
(3) calcium sulfide
B. K2O (1) dipotassium oxide
(2) potassium oxide
(3) potassium oxygen

8. Solution
Select the correct name for each of the following ionic compounds. A. CaS (3) calcium sulfide B. K2O (2) potassium oxide

9. Metals with Variable Charges
Transition elements and representative metals of Groups 4A (14) and 5A (15), such as Pb, Sn, and Bi,
can lose s electrons from its highest energy level as well as d electrons
can form two or more positively charged ions
are described as having a variable charge
Exceptions are zinc, silver, and cadmium, which only form one ion (Zn2+, Ag+, and Cd2+).

10. Metals with Variable Charges
For metals that form two or more different ions, a Roman numeral equal to the ionic charge is written in parentheses after the metal name.
For example,
Fe2+ is named iron(II)
Fe3+ is named iron(III)
Cu+ is named copper(I)

11. Metals with Variable Charges

12. Metals with Variable Charges

13. Guide to Naming Compounds with Variable Charge Metals

14. Naming Compounds with Variable Charge Metals
Step 1 Determine the charge of the cation from the anion.
Formula
Fe2O3
Elements
Iron (Fe) Oxide (O)
Groups
Transition Group 6A (16)
Element
Ions
Fe? O2−
Charge
Balance
2(Fe?) + 3(2−) = 0,
Fe charge is 3+.
Fe O2−

15. Naming Compounds with Variable Charge Metals
Step 2 Name the cation by its element name, and use a Roman numeral in parentheses for the charge. Iron(III) Step 3 Name the anion by using the first syllable of its element name followed by ide. oxide

16. Naming Compounds with Variable Charge Metals
Step 4 Write the name for the cation first and the name for the anion second. Iron(III) oxide

17. Names of Compounds with Variable Charge Metals
Examples of compounds with variable charge metals include:
Compound
Systematic Name
FeCl2
Iron(II) chloride
Fe2O3
Iron(III) oxide
Cu3P
Copper(I) phosphide
CuBr2
Copper(II) bromide
SnCl2
Tin(II) chloride
SnS2
Tin(IV) sulfide

18. Writing Formulas from the Name of an Ionic Compound
Ionic compound formulas are written from
the first part of the name that describes the metal ion, including its charge
the second part of the name that specifies the nonmetal
Subscripts are added to balance charge.

19. Guide to Writing Formulas from the Name of an Ionic Compound

20. Writing Ionic Formulas from the Name of an Ionic Compound
Write the formula for chromium(III) bromide. Step 1 Identify the cation and the anion. The Roman numeral (III) indicates that the charge of the ion is 3+, Cr3+.
Type of Ion
Cation
Anion
Name
chromium(III)
bromide
Group
transition element
7A (17)
Symbol of Ion
Cr3+
Br−

21. Writing Ionic Formulas from the Name of an Ionic Compound
Write the formula for chromium(III) bromide. Step 2 Balance the charges. Step 3 Write the formula, cation first, using subscripts from the charge balance. CrBr3

22. Learning Check
Write the name for each of the following ionic compounds. A. Li2S B. SnCl2 C. Al2O3 D. ZnO

23. Solution
Write the name for each of the following ionic compounds. A. Li2S lithium sulfide B. SnCl2 tin(II) chloride C. Al2O3 aluminum oxide D. ZnO zinc oxide